Question: why is the accountsd process eating so much cpu?

Response:
To address issues with iCloud services or high CPU usage due to Mail accounts, you might consider logging out of all iCloud services, rebooting your device, and then logging back in again.
Multiple people have also reported that deselecting the option "> Preferences > Accounts > Advanced > Automatically Detect and Maintain Account Settings" in Mail's preferences under Accounts and then Advanced can be effective in reducing CPU usage.
Others have reduced CPU usage from the Mail app by going to Window > Activity and canceling all processes.
Additionally, accountsd appears to have a bug in the file indexing, which causes it to get stuck in a loop while indexing the files; this bug may be related to data in iCloud.
Finally, it appears that a having a Gmail account signed into your Mail app may cause a problem: some have reported that removing the account can significantly reduce CPU usage and cool down your system.


Question: what does the (!) mean after uptime on htop

Response: The exclamation mark in htop indicates that the server has been operational for 100 days or more; while this was a point of pride in the past, a server being up for so long now likely indicates that it isn't up to date with kernels.


Question: why use openid connect instead of plain oauth2?

Response:
OpenID Connect is considered more robust than OAuth.
It will provide both an access token and an ID token, which standardizes aspects that OAuth2 leaves to choice.
OAuth strictly provides authorization, while OpenID Connect, built on OAuth 2, supplies authentication information but does not offer a more robust implementation than OAuth.
OpenID Connect allows applications to retrieve information about authenticated users and assures the information's validity.
OpenID Connect makes it significantly harder to steal access tokens compared to using OAuth alone.
OpenID Connect affords a secure, centralized authentication solution, particularly for mobile software, which includes new security features recommended by Google.


Question: aggregation vs composition

Response:
Aggregation, as distinguished from ordinary composition, diverges significantly by not implying ownership.
In composition, the demise of the owning object results in the simultaneous destruction of the contained objects.
When examining composition, it can be perceived as 'needs a,' where the relationship denotes a necessity, such as a car needing an engine.
Conversely, aggregation is akin to 'things related for a purpose'.
In the realm of composition, the relationship "A owns B" implies a strong association, signifying that B has no independent meaning or purpose within the system without "A".
On the other hand, in aggregation, the relationship "A uses B" conveys a weaker association, allowing B to exist independently, both conceptually and functionally, from "A".
Furthermore, the strength of association is emphasized by stating that composition is a robust association, while aggregation embodies a weaker form of association.
To illustrate this concept further, one can consider a simple example: an array of objects exemplifies composition, where the deletion of the array results in the vanishing of its contents.  Conversely, an array of pointers to objects represents aggregation, allowing the array to vanish without affecting the existence of its members, unless a specific method is employed to delete each object as its pointer is removed.


Question: how can i view hidden files in the finder?

Response:
To enable the Finder on your Mac to display all files, including those that are normally hidden, you can execute the following command prompt in Terminal: defaults write com.apple.Finder AppleShowAllFiles -bool YES; killall -HUP Finder.
Alternatively, as a simpler and safer approach, you can navigate to the finder menu bar, select "Go/Go to folder", Type the path to the invisible folder, in this case the top directory first slash of /folderName/, and it will reveal the contents without using the terminal.
An even quicker method is to navigate to Finder, click on Go Hold down Option key, and hidden directories & files will appear.
To toggle the visibility of hidden files in Open/Save dialogs, a shortcut involving CMD/shift/.(period) can be used.
To hide defaults again, write com.apple.finder AppleShowAllFiles -bool FALSE killall Finder.


Question: what does systemctl daemon-reload do?

Response:
The process of executing `systemctl daemon-reload` involves re-running all generators, which dynamically generate unit files and manage additional dependencies.
This action allows systemd to incorporate changed configurations, reloading unit files, and recreating the dependency tree without affecting sockets listened to by systemd on behalf of user configurations.
Generators play a crucial role in this process, converting non-native configuration files into native unit files and can be found in specific directories like /usr/lib/systemd/user-generators/.


Question: tar: removing leading `/ from member names

Response:
To avoid "Removing leading `/' from member names" messages in tar operations, one can use the -C option to change the working directory to the root (/) then specifying the file tree to archive without a leading slash.
Go go to the parent directory and execute the command there: ``cd /var/www/ tar -czf mysite.gz mysite.
Similarly, using `cd /home/foo && tar czf ~/backup.tar.gz` to avoids putting absolute paths into the tar archive.
Moreover, using the -C option prevents compressing with complete paths with `root@server # tar fcz bkup.tar.gz -C /home/ foo/`.
When specifying the archive's path, one might see informational messages; using the -P option either like `tar -zvcf /tmp/mike.tar.gz -P /tmp/mike` or `tar -zvcf mike.tar.gz -P /tmp/mike` or `tar -zvcf mike.tar.gz /tmp/mike` appropriately can resolve this.


Question: is there such a thing as having too many unit tests?

Response:
Indeed, there can be an excess of unit tests, which may result from duplicative tests, those that are unnecessary, or tests that become a maintenance burden.
Pragmatically, the focus should be on tests that cover the primary entry points to ensure they function correctly and handle critical edge cases rather than seeking a suite of tests with redundant coverage.
Bulk testing, comparison against brute-force implementations, and random test case generation can be effective for complex algorithms.
Tests for newly discovered bugs and odd special cases are also beneficial.
It's important to test units, not just sub-units, and to integrate unit testing with higher-level tests for a more efficient effort.
Reach a certain test coverage across all classes before striving for complete coverage on subsequent modifications to maintain balance.
In cases of test maintenance overshadowing development, it may be necessary to reassess or even dispose of the less valuable tests.
Lastly, while code coverage is a good target, the quality of the tests and their alignment with crucial functionality take precedence.


Question: what is the difference between an adt and a data structure?

Response:
An ADT (Abstract Data Type) is more of a logical description, while a Data Structure is concrete.
Think of an ADT as a picture of the data and the operations to manipulate and change it.
A Data Structure on the other hand is the real, concrete thing that can be implemented and used within an algorithm.


Question: how to get keycodes for xmodmap?

Response:
The tool 'xev' should normally generate KeyPress and KeyRelease events for keys such as Alt and Super when pressed.
If 'xev' is not functioning as expected, it might be due to other processes intercepting the keypress or causing the window to lose focus.
One can run 'xev' in an otherwise empty X server to ensure no other applications are interfering.


Question: why php is not used by big companies?

Response:
For major transactional sites, the associated risk management costs make it more economical and secure for large corporations to opt for applications developed in .NET rather than PHP.
The banking industry, prioritizing security and unbothered about costs, tends to favor .NET over PHP, given the latter's perceived lack of features in this critical area.
Additionally, the difficulty in developing a secure PHP application without encountering major flaws often leads to higher costs compared to enterprise-level .NET applications.
Moreover, some big companies have existing infrastructure, sometimes in Java, predating the emergence of PHP, making it less sensible to introduce PHP into their technology stack.
Notably, PHP's perceived limitation as a web-only language further diminishes its suitability for applications beyond the web front end, contributing to its limited adoption in certain corporate environments.


Question: how to start tmux with attach if a session exists

Response:
A variety of methods are available to ensure tmux sessions are handled effectively; for instance, you can use the script '/somewhere/on/your/path/ttmux', or set it up as a shell function: `#!/bim/sh #`.
It's also possible to create an alias that starts a new tmux session if attaching to an existing one fails, using `tmux attach || tmux new`.
You can also simply add a line in your ~/.tmux.conf file: `# if run as "tmux attach"`, which allows tmux to automatically create a new session if one doesn't exist when you attempt to attach.
If your version of tmux supports it, using the 'new-session' command with the appropriate flags will let you attach it to an existing session named `-A -s main` or create it if necessary.
For versions earlier than 1.8, you can use tmux attach || tmux.
Additionally, checks can be incorporated into your .bashrc to prevent double-nesting of sessions, like in `if [ -z "$TMUX" ] && [ ${UID} != 0 ] then tmux new-session -A -s main fi`.
Another approach involves checking the existence of a session before trying to attach to it using `session="main" #` then discard output #.
Lastly, for a simpler alternative, leveraging the ` $ tmux a || tmux' command can streamline the process.


Question: unzipping a .gz file without removing the gzipped file

Response: To unzip a .gz file without requiring a temporary file, use the command: `zcat somefile.gz > somefile`.


Question: how to set up reverse tethering over usb?

Response:
SimpleRT is an effective tool for use with Linux for reverse tethering.
The Android Usb Port Forwarding app offers functionalities for the same purpose.
Windows users with rooted phones can utilize Another resourceful tool found on the xda-developers forum, named Android Reverse Tethering.
For those seeking an app solution, the Reverse Tether app is available on the Play Store providing free limited trial use, with full features for a fee.
Rooted Android phone users can connect their Android device via USB, and activate USB tethering by navigating to Settings → More...→ Tethering & mobile hotspot → USB tethering.
Importantly, ReverseTethering NoRoot's app exists, allowing reverse tethering without root requirements on unrooted Android devices.
Moreover, for Windows, Linux or Mac PC, gnirehtet is a project that permits reverse tethering by downloading and running a command from the gnirehtet zip-file without the need to pre-install an app.


Question: where did the wheel group get its name?

Response:
Information from Wikipedia indicates that the term is derived from the slang term "big wheel" is a slang used referring to a person with great power or influence; the term comes from BSD.
Moreover, the term "big wheel", a popular expression after World War Two, is further associated with the phrase "rolled a big wheel," indicating importance and influence, commonly used by mechanics.


Question: what is the difference between echo and print in shell script?

Response: When comparing "printf" and "echo," the former offers additional formatting capabilities: specifically, it doesn't automatically append a new line to the output, contrary to "echo," which does.


Question: os x yosemite xcode update stuck on waiting

Response:
If you encounter the issue of the OS X Yosemite Xcode update being stuck on "Waiting," one option is to download and install the Xcode DMG directly from the Apple Developer Account website if you have one such account.
Alternatively, consider clearing your cache and restarting the download from the App Store.
However, some users have found that patience is key, and waiting for some time eventually resolves the problem.
Another approach involves moving Xcode from your Applications folder to the trash bin, which has worked for some users.
If these methods do not resolve the issue, you can open the App Store, initiate the update, and then click on "Store" in the top-left menu, choose "Check for Unfinished Downloads," enter your Apple ID and password, and the update process should proceed smoothly.


Question: is rsa a block cipher?

Response:
RSA does not fall into the categories of either a stream cipher or a block cipher.
This is evidenced by the fact that RSA utilizes asymmetric keys which means it has distinct encryption and decryption keys, contrasting with the symmetric keys used in both stream and block ciphers.
However, there is a discourse suggesting that RSA could be considered a block cipher if the symmetric key requirement is disregarded.


Question: how do you move all files (including hidden) from one directory to another?

Response:
One method to move files using the shell is the command `#!/bin/bash shopt -s dotglob mv Foo/* Bar/`, which includes filenames starting with a '.' in the pathname expansion.
Another approach is utilizing the find command with the structure `find Foo/ -type f -exec mv -t Bar/ {} \+`, where "type f" restricts the find command to finding files.
In zsh, you can use the syntax `mv Foo/*(DN) Bar/` or `setopt -s glob_dots`.
A simple solution in bash to include hidden files but exclude directories is the command `mv {Foo/*,Foo/.*} Bar/`, applying a test within a for loop to ensure only files are moved.
Rsync also offers a viable method with the command `rsync -axvP --remove-source-files sourcedirectory/ targetdirectory`; however, it leaves behind an empty directory structure.
Lastly, for bash, a working command without altering shell options is `mv sourcedir/{*,.*} destdir/`, and for more complex file selections, you can expand the expression in the curly braces.


Question: how to install and use gnu grep in macos

Response:
Run the command "brew install grep" like you would with coreutils.
After installation, to use the commands with their normal names rather than with a 'g' prefix, you should add a "gnubin" directory to your PATH in your bashrc.
This might include adding the line "PATH="/usr/local/opt/grep/libexec/gnubin:$PATH"" to your bash configuration.


Question: execute a command once per line of piped input?

Response:
Xargs execute command and they are a good general tool for the job.
Furthermore, GNU Parallel is also recommended for these kind of tasks: `cat stuff | grep pattern | parallel java`.
Additionally, another user offers a copypaste that can be used immediately: `cat list.txt | xargs -I{} command parameter {} parameter`.


Question: the volume cant be ejected because its currently in use

Response:
When encountering issues with ejecting a disk due to a message suggesting that files are still open, running Disk Utility or, if necessary, DiskWarrior could resolve the problem by repairing the potentially corrupt file system, thereby allowing the disk to become ejectable once more.
Alternatively, attempting to relaunch the Finder may also be effective in resolving disk ejection issues.


Question: how to list all files ordered by size

Response:
To sort files by size, execute the command `ls -lS /path/to/folder/` with 'Capital S' signifying size sorting.
For more information on the `ls` command, particularly sorting by file size, look up `man ls -S`.
Specify `ls -ldU -- /*(.OL)` for a reverse order file list display using `zsh` and `GNU ls`, where `(.OL)` is a zsh glob qualifier that selects regular files only and sorts in descending order by file size.
If you want to include hidden files (whose name starts with a dot, except . and ..) and search in hidden directories as well, add the D globbing qualifier: print -rl -- /*(.DOL).
The command `find . -type f -exec ls -lSd {} +` applies to recursively search and list files in size order.
Alternatively, use `find . -type f -ls | sort -r -n -k7` to sort files with the `-ls` option and numerical sorting.
On GNU/Linux systems, to get a human-readable file size list in descending order, the command `find . -type f -print0 | xargs -0 du -h | sort -rh` is used.
To reverse file list display order by size with basic `ls`, one would employ `ls -lSrh`, with `-h` introducing human-readable sizes.
Use `ls -lSr` when a detailed ascending order list by size is necessary.
Use this script `#!/bin/bash find ${1:-.} -maxdepth 1 -type d -exec du -sm {} \; | sort -nr | sed -E 's/^([0-9]+)/\1M/g'` to see cumulative sizes of files in subdirectories.


Question: can i create a shortcut to open a specific application on os x?

Response:
While Mac OS X does have a built-in method for setting keyboard shortcuts, it doesn't work for Firefox.
Karabiner-Elements allows for customization of keyboard shortcuts on Mac versions 10.12 and later, including executing shell commands.
Alfred, particularly in its Power Pack version, offers the ability to map shortcuts to applications, among its various features.
Using Automator Services in combination with built-in keyboard shortcuts is another method to create shortcuts without third party apps.
Spark 3 is a free Shortcuts manager which enables you to create Hot Keys to launch applications and documents, execute AppleScript, control iTunes, etc.
Some users have found Apptivate to be the easiest to use for assigning global shortcuts to apps.
To open Terminal with a shortcut on Mac without third-party software, one can utilize a custom Quick Action created in Automator and assign it a unique hotkey, like ⌘ + ⌥ + F12.
For iTerm2 users with Oh My Zsh, one can replace AppleScript with the 'Launch Application' action in Automator.
Furthermore, Terminal app already has built-in shortcut keys for opening new terminals or tabs at a folder location: New Terminal at Folder ^+⇧+T New Terminal at Tab Folder ⌥+^+⇧+T.


Question: how do i disable system integrity protection (sip) aka rootless on macos [os x]

Response:
To disable SIP on a Mac, you should use the command 'csrutil disable' in the Terminal window while in Recovery Mode, then restart your Mac.
If accessing the Recovery Partition is not an option, you could attempt to disable SIP with the 'nvram' command, using 'sudo nvram boot-args="rootless=0"'.


Question: which security measures make sense for a static web site?

Response:
To ensure the security of data transmission for your website, you should consider utilizing HTTPS Strict Transport Security and Certificate Pinning to protect against data sniffing and manipulation.
It's also wise to implement a Content Security Policy, especially if your website incorporates external content like ads or social media buttons, to restrict unauthorized content.
Clickjacking protection is recommended to prevent your website content from being framed by unauthorized sites, though it does not harm if your site does not need such framing.
If you roll out HTTPS for your website, following up with HSTS is a logical step, as it enforces secure connections and prevents certain types of attacks.
For static websites, these security measures might be considered less urgent, but they are still important to consider for future-proofing and adapting to dynamic changes.
The belief that static websites do not require SSL certificates has changed, particularly with search engine rankings and browser treatments being influenced by the presence of HTTPS.
Furthermore, utilizing HSTS adds a layer of security on top of HTTPS, helping both the websites and their users.
HPKP is an effective method to combat malicious certificates, but it must be used correctly.
The consensus across discussions is that while static sites may seem to have fewer risks, security aspects like HTTPS, HSTS, and Content Security Policy (CSP) are still important for protecting against various threats and maintaining site integrity.


Question: why 2des is not secure?

Response:
Two-DES does not provide the expected increase in security due to its susceptibility to certain types of attacks, specifically the "meet-in-the-middle attack".
Despite employing 112 key bits, 2DES only achieves a security level equivalent to about 257 bits rather than 2112. .
Conversely, although 3DES uses 168 key bits, it effectively offers a security level of 2112 bits, which is considered sufficiently secure for most applications.
The reason 3DES is preferred to 2DES is that 2DES doesn't actually give that much more security than DES.


Question: how to export variables from a file?

Response:
source tmp.txt export a b c ./child.

set -a . ./tmp.txt set +a set -a causes variables¹ defined from now on to be automatically exported; you can also use set -o allexport as a more descriptive alternative way to write it (set +o allexport to unset).

Try: while read LINE; do export "$LINE"; done < ./tmp.txt.

A dangerous one-liner that doesn't require source: export $(xargs <file).

This solution will export all key=values to environment variables that are in .env file, that are not empty lines or commented (#): File: .env ENV=local DEBUG=True; Command: $ export $(cat .env | egrep -v "(^#.*|^$)" | xargs).


Question: how can i get my external ip address in a shell script?

Response:
The command `wget -O - -q http://whatismyip.org/` can be used to find your IP address, as can `netcat icanhazip.com 80 <<< $'GET / HTTP/1.1\nHost: icanhazip.com\n\n' | tail -n1` to achieve the same result.
Another alternative is to use `ifconfig.me`, which offers additional functionality available on its website.
If you prefer using HTTPS, you could use a command pattern like `_result=$(wget -qO- https://ipcheckit.com/) _result="${_result##*Your IP address is<br><b>}" printf '%s\n' "${_result%%</b></p>*}"`.
Furthermore, for those managing dynamic IP addresses, registering at a service like no-ip.com and using their update tool can be beneficial (external_ip=`dig +short xxx.no-ip.org`).
You can retrieve the IP with the command `external_ip=`dig +short xxx.no-ip.org``.
The website `curlmyip.com` provides a simple and memorable way to find your IP with commands like `curl curlmyip.com`.
Instead of HTTP requests, you can directly get your IP from a DNS server using commands such as `dig @resolver4.opendns.com myip.opendns.com +short`.
To get your IP address through a command line, you could use `wget -q -O - checkip.dyndns.org | sed -e 's/[^[:digit:]\|.]//g'`.
Several other commands like `curl ident.me`, `curl ifconfig.me`, and `curl https://tnx.nl/ip` are also at your disposal for the same purpose.
If you want to display the current IP address in a popup window, you might use `zenity --info --text "$(curl -s icanhazip.com)"`.
Alternatively, for automated queries, `use STUN` with the command `stunclient stun.services.mozilla.com` and specific data parsing for the IP address.


Question: does filevault encryption slow read/write access on an ssd?

Response:
FileVault 1 was known to noticeably slow down the system.
The performance degradation with FileVault 2, however, is reported to be extreme and should be avoided for all who spent money upgrading to an SSD.
In contrast, some users have found that the slowdown with FileVault 2, such as on a Samsung 840 EVO in an early 2011 MacBook Pro running Mavericks, is not noticeable.


Question: how to connect airpods to apple watch only?

Response: The Airpods should automagically connect to the Watch once you set them up on your phone using iCloud, but if you need to pair them to the watch manually, you can do it like you would with any bluetooth headset.


Question: how does the mac choose which connection to use when both wifi and ethernet are connected?

Response:
When attempting to connect to the internet or network on a Mac using multiple active connections, the operating system, OS X, will prioritize the connection type listed at the top within its network settings.
Additionally, despite any set order of service, Mac OS has been observed to favor WiFi connections over Ethernet even if Ethernet is positioned higher in the list.


Question: do i need to encrypt connections inside a corporate network?

Response:
Encrypting connections on intranet resources over HTTP is necessary.
As long as no one else connects to the network and there are no technically proficient individuals within, it remains secure.
However, traffic on an unsecured network by itself poses a security threat, even without hackers, due to the potential for repudiation issues.
Anything not encrypted is vulnerable to attackers, and encryption is a measure to meet compliance standards like GDPR.
A thorough threat and risk analysis should determine the necessity of encryption within your organization.
Lastly, leaving credentials unencrypted contradicts the necessity of using login credentials; if you cannot drop the login form, do not send credentials unencrypted.


Question: block apps from accessing the internet on android device

Response:
If you do not have root access to your device, you can use the Mobiwol app to control the access apps have to the internet.
Another option is the APK app Net Blocker, which allows you to block network access for specific apps and notifies you when networks are blocked.
Disabling the network when the app is in the foreground or hibernating it when in the background can also help control app network access without root.
The No-Root Firewall app is suggested for controlling what apps have internet access without the need for root access.
Droidwall is an app that can control network access but requires a rooted Android device.
Several apps like Mobiwol, NoRoot Data Firewall, and LostNet NoRoot Firewall do not require root access, while Root Firewall, MsWall Firewall, Advanced Firewall, DroFirewall, Antivirus, and Security Firewall Plus necessitate it.
Users of CyanogenMod have a built-in Privacy Guard feature available to prevent apps from using the internet.
Google's solution, Datally, also requires no root and helps control mobile data use.


Question: why dhcp request is broadcast?

Response:
The client does not have an IP address until the server sends a DHCPACK.
A broadcast is sent to inform other DHCP servers that may have sent offers that their offer has not been accepted.
This ensures that any server that could have issued an offer is updated about the client's selection through the broadcasted request message.


Question: how to make a machine accessible from the lan using its hostname

Response:
You will need to configure your other systems to use some kind of name lookup service; for example, you can bind and enter all local machines inside a local domain, then have it serve DNS for that site.

In order to access machine B from machine A using the name of machine B, machine A has to have some way to map the name of B to its IP address, so to add an entry for B in the hosts file of A: Determine the IP address of B, then connect B to the network, and it should get the IP address you specified and will be reachable by the specified name from any machine in the network.

Vi /etc/dhcp3/dhclient.conf send host-name “ubuntu-laptop”; and /etc/init.d/networking restart.

Use Multicast DNS (mDNS), or you can create an A type subdomain that points to your internal IP.


Question: can i change the behavior of the home and end keys on an apple keyboard with numeric keypad?

Response:
One option is to create ~/Library/KeyBindings/ and save a property list in the Library/KeyBindings directory and save it as DefaultKeyBinding.dict, although this may not be supported by all applications.
It might be easier to just use the default keybindings.
Another option is to enable the "Use PC Style Home/End" setting in Karabiner, which is defined in Resources/include/checkbox/for_pc_users.xml.
The tool keyremap4macbook, which is free and compatible with Macs, is recommended for easily changing the default home/end buttons behavior.
Additionally, the latest version of Karabiner requires downloading specific settings from their website and following a process to import and activate "PC-Style Shortcuts".


Question: whats the meaning of a dot before a command in shell?

Response:
A dot in that context means to "source" the contents of that file into the current shell; it is shorthand for the bash built in source, that is, it is the same as the source code.

In other words, . (source or dot operator) means read and execute commands from the filename argument in the current shell context.


Question: nmap do not show filtered ports?

Response:
When scanning with Nmap and the status of a port is ambiguous, indicated as either open or filtered, this could be due to a packet filter dropping the scanning probe or any response that might have been elicited.
Also note that the Nmap default only scans the most common 1,000 ports, so if yours isn't reported, it may be outside that group; to ensure that Nmap scans certain ports, you can specify which ones to scan using the -p option.


Question: where are whatsapp voice notes stored on android?

Response:
Your voice files are also stored in the Whatsapp folder.
The specific path for your voice notes is: WhatsApp/Media/WhatsAppVoiceNotes/.


Question: why do we use story points instead of man days when estimating user stories?

Response: The purpose of the estimation process is to improve over time by allowing estimators to maintain consistent metrics rather than having to adjust for previous underestimations in each new estimate.


Question: why isnt itunes shuffle random?

Response: To reshuffle the play order in music software like iTunes, you need to deactivate and then reactivate the random play feature.


Question: can you connect airpods and headphones at the same time mac?

Response:
While it is possible to use multiple different types of Bluetooth devices simultaneously, such as a mouse, keyboard, and headphones, you cannot use more than one of the same type of device at the same time.
However, it is possible to share audio from a MacOS Macbook Pro with two or more Bluetooth headphones by creating a Multi-Output Device through the Audio Midi Setup in Utilities.
This setup will allow sound output through both headphones, although you will no longer be able to adjust the volume from the Macbook directly, but rather individually on each headphone.


Question: recursion or while loops

Response:
Some problems are very amenable to recursive solutions, e.g. quicksort, while some languages don't really support recursion, e.g. early FORTRANs.
Recursion has more expressive power than iterative looping constructs, as it allows for writing loops without the need for mutable data.
It is acknowledged that recursion is often less obvious and therefore more challenging to maintain compared to iteration.
Recursion is not intrinsically better or worse than loops - each has advantages and disadvantages, and those even depend on the programming language and implementation.
In instances where the recursion depth exceeds the programming language’s default limit, as encountered in Python, loop constructs might be preferred if the stack size is not enough.
Recursion is about repeating call to function, loop is about repeating jump to place in memory.


Question: is the nhs wrong about passwords?

Response:
NHS's suggestion that short passwords are more secure is incorrect, as longer passwords with a mix of characters have a higher number of possible combinations, making them more secure.
It's also acknowledged that the NHS wrong about which passwords are most secure and that certain outdated systems may truncate passwords, thus reducing the security of longer passwords if the systems only recognize a limited number of characters.


Question: are #regions an antipattern or code smell?

Response:
The use of #regions in code has generated diverse opinions within the software development community, with some considering it a sign of code smell.
Particularly, a method with an extensive number of lines or regions is identified as a clear indication of a code smell.
While the term "anti-pattern" is commonly associated with program logic or design patterns, it's argued that the use of regions is more aligned with the layout of a text editor, making it less fitting for such classification.
A rule of thumb is proposed, suggesting that having more than five regions in a file can be considered a code smell.
The concept of #region blocks is likened to "Febreze for code," serving to conceal code smells rather than addressing them directly.
Moreover, software engineering that may be commonly used but is ineffective and/or counterproductive in practice regions are anti-patterns.


Question: why is root login via ssh so bad that everyone advises to disable it?

Response:
Direct root login might lead to increased damage if a brute force attack is successful.
Additionally, misconfigurations related to "passwordless" SSH keys could unintentionally expose your machine to the internet.
It's essential to acknowledge the presence of bots that actively attempt to gain access to computers via SSH by using common passwords like "root" or "password123".
Restricting root access over SSH complicates a bot's task as it would then have to guess both a valid username and the corresponding password.


Question: how can i execute local script on remote machine and include arguments?

Response:
Sample script: $ more ex.bash #!/bin/bash echo $1 $2, for example: $ ssh serverA "bash -s" < ./ex.bash "hi" "bye".

You can pacify bash by terminating it from taking any of the remaining command line arguments for itself using the -- argument.

You can also simply hardcode it.


Question: can airpods connect to iphone and mac?

Response:
When your other devices are signed in with the same Apple ID as your iPhone, AirPods connect automatically with all your Apple devices, automatically switching between your iPhone, iPad, iPod touch, and Mac.

Seamless switching appears to work from iOS 14, iPadOS 14, and macOS Big Sur; your devices need to have Bluetooth 4 in order for the AirPods to work seamlessly.

However, the developer of an App called ToothFairy claims that AirPods have to be manually switched from iOS to Mac, which you can do from the Bluetooth menu on the Mac, and the App makes this easier.


Question: update bash to version 4.0 on osx

Response: Apple does not update to bash 4 due to GPL license restrictions, however, you can install bash 4 via Homebrew and even make it your default shell: after installing the newest version using Homebrew, add the new bash path to the /etc/shells file and use chsh to change your default shell.


Question: how to download music from a different apple id?

Response: You cannot change 'ownership' of the files to another account, but you can turn on Home Sharing on both machines, then add this music to the new library, and use your account to authorize it; alternatively, you could possibly copy the files into the library, use iTunes Match to download the files from iTunes in the Cloud, then delete the local files.


Question: is using git for deploying a bad practice?

Response:
Some would say that there is nothing wrong with using Git for deployment, and it is, in fact very good practice and pretty common, as it's a lot less prone to errors than copying files over ftp or rsync.

However, others suggest that while it is fine for small projects, it does not scale very well.


Question: how do i make `ls` show file sizes in megabytes?

Response:
To make `ls` show file sizes in megabytes, you can use ls -lh, which gives human-readable file sizes in long format and uses k, M, G, and T suffixes.
Alternatively, you can use --block-size=MB, specifying the block size in megabytes, for example, --block-size=1M.


Question: how to change the name of my apple pencil?

Response: On iOS 12.1.1 and earlier versions, it's not possible to personalize the names of Apple Pencils.


Question: route servers and looking glasses - what are they?

Response:
A looking glass is usually a website (most often CGI) that interfaces with routers that are owned and operated by a single ISP or other network operator.
The difference between a public route server and a looking glass (aside from an LG having a nifty CGI) is that a wide variety of networks (including some tier one carriers) peer with a route server, so there's an "overall" bigger picture of which prefixes are coming from which ASN's.
A route server itself is an eBGP speaker, however there have to be specific considerations for a route server and multilateral BGP peering.


Question: what do i type to produce the command symbol (⌘) in mac os x?

Response:
To input special characters and symbols on a Mac, go to System Preferences and navigate to Keyboard, then Input Sources, where you can click "+".
Now, scroll to "others" and select "Unicode Hex Input" before clicking the "Add".
Alternatively, in OSX Lion you can press Cmd-Ctrl-Space, type "pla" into the search bar, and then hit Return twice.
Another option is to download the BetterTouchTool app, in which you need to select 'Keyboard', click 'Add New Shortcut, and set the keyboard shortcut to 'Option+C'.
Then, set trigger predefined action to 'Paste predefined text' and copy '⌘' into the box before clicking 'OK'.
Now, when BetterTouchTool is open, all you have to do is press 'Option+C' and it automatically types the '⌘' symbol.
For future reference, you can copy and paste the following: ⌃ for Control, ⌥ for Option (alt), ⌘ for Command, and ⇧ for Shift.
Also, Keyboard Maestro, allows for the creation of a macro that inserts a "⌘" symbol whenever "=cmd" is typed.
This can be done by creating a new macro and giving it a name like "insert ⌘", then add "Typed String Trigger": =cmd and add "New Action" before choosing "Insert Text by Pasting".
Finally, by pressing "control+command+space" in any application and typing "place of interest", you can find the glyph for Command (super).


Question: how do i take a screenshot without the shadow behind it?

Response:
You can enter a command into Terminal: defaults write com.apple.screencapture disable-shadow -bool TRUE.
After executing this command, either reboot the system or restart the UIServer using the killall SystemUIServer command.
Another option to alter shadow effects in screenshots is the screencapture utility.
TinkerTool provides a feature to remove screenshot shadows as well.
Additionally, you can remove the window shadow from screenshots by holding the Option key while clicking after initiating the screenshot command, combining Shift, Command, 4, and Space.


Question: why can i traceroute to this ip address, but not ping?

Response:
Pings can be blocked (ICMP block) on a remote host but traceroute can still find the route to it using standard network routing UDP or TCP/IP.
The ping utility relies on the ICMP protocol which is sometimes blocked at the network firewall or the firewall on the device itself.


Question: how to make google chrome helper not use as much cpu

Response:
It's advisable to disable extensions temporarily to see if one of them is potentially causing the issue with CPU usage.
Limiting Chrome's resources might help, and tools like cputhrottle can assist in limiting system-level usage.
If uninstalling system-wide Flash and the one that is embedded within Chrome are not an option, you should at least prohibit it from autoplay, as well as controlling plugins and extensions, which could be misbehaving.
 It can also help to use different browsers or different profiles for one browser.
Try opening Chrome Menu → Window → Task Manager to see what exactly consumes CPU, and also watch for ad content and ad blockers.
Disabling each extension one by one might reveal a problematic one, such as an Adblocker.
Site-specific issues can cause CPUs to spike, as one user experienced with a website like Okta.
Finally, another user found that an ad blocker was consuming up to 40% of CPU.


Question: what alternatives are there when ssh is being actively filtered?

Response:
One could employ VNC for their needs, yet it is imperative to note that without the protection of a VPN or SSH, the security of such a method is questionable.
Secure data transmission can be maintained through methods like https, and the use of tools like Corkscrew and Netcat, both of which aid in using HTTPS proxies to encapsulate SSH traffic.
In instances where HTTPS remains unfiltered, leveraging AJAX or HTML5-based terminal emulators running on a secure site could serve as a viable alternative.
Alternatively, if one seeks to tunnel IP through different protocols while using Corkscrew, options like implementing IP/DNS with iodine or IP/ICMP present themselves, along with resources such as http://www.serfish.com/console/.
For those who can initiate server access through another route to install daemon, the installation of telnet-ssl/telnetd-ssl is a relatively straightforward and efficient solution.
Tunneling SSH over DNS via OzymanDNS or iodine is also a practical consideration.
Should internet connection be subject to filters, turning to alternative connection methods like satellite internet service providers can circumvent such barriers.
Adjusting the SSH port to 443 to enable connection through it has been advantageous against certain firewalls, although its efficacy can vary.
Dividing the SSH handshake into multiple packets and potentially sending them out of sequence can evade packet filtering technologies that operate on a single packet level.
Lastly, substituting SSH with MOSH, which uses SSH for authentication and then transitions to a UDP-based communication, can yield a faster and more reliable connection.


Question: wi-fi disconnects when i lock the mac

Response:
If your WiFi disconnects when your Mac is locked, one solution is to open Terminal and execute specific commands (like "cd") that prevent the WiFi from disconnecting when logging out.
You can also determine the specific network interface for your WiFi and apply settings using the airport utility for your wireless card to ensure it doesn't shut off.
Alternatively, you can install an app like "Lock Me Now" which provides a "Just Lock" option to avoid WiFi disconnection when the screen is locked.


Question: zip all files in directory?

Response:
Use the command "zip -r myfiles.zip mydir" in Unix, where "mydir" is the directory to be zipped.
Alternatively, you can use "find" and "xargs" to locate files and then compress them into a zip archive.


Question: does the shebang determine the shell which runs the script?

Response: Yes, the shebang determines which shell runs a script: the line contains a path to the bash interpreter, ensuring the script is interpreted by bash, regardless of the executing shell.


Question: why does everyone use git in a centralized manner?

Response:
Utilizing Git centrally provides the advantage of maintaining a gold standard of the current state of the project, ensuring a reliable reference point while facilitating improved code-sharing mechanisms.
In a development environment, where code must converge, a centralized server, often a CI server, is a natural point for code coalescence and building the product.
This central repository in Git allows other developers to conveniently pull down changes at their discretion, eliminating the need for constant checks on a central server like SVN.
Pulling "all colleagues' changes vetted in the central repo" becomes more convenient and scalable, particularly when there's a lack of specific interest in particular changes or colleagues' work.
Additionally, using Git in a centralized manner allows for flexible commit practices, such as squashing work-in-progress commits together.
The reliability of a central 'truth' CI server, almost always available, adds to the appeal of the centralized Git workflow.
Business logic also favors a centralized server, aligning with realistic business scenarios, and using Git ensures access to the distributed side for handling complex situations.
The decision to use Git centrally is also influenced by considerations of complexity and the need for consistency in the workflow.
Furthermore, the organizational structure of companies, often centralized, reflects in their workflow, and tools like Git are adapted to this chain of command, with the decentralized aspect often being a feature that may not be needed in such contexts.


Question: are macs vulnerable to the bash shellshock bug?

Response:
To determine if your system is affected by the "Shellshock" vulnerability, a specific command can be typed in your shell: env x='() { :;}; echo vulnerable' bash -c 'echo hello', and if it says vulnerable, then you are vulnerable.
According to another opinion, all Mac OS X machines are technically vulnerable to “Shellshock,” until Apple issues a security update.
However, it is advised that you are only truly vulnerable if someone you don't know can remotely access your machine and in such a way to be able to execute a Bash command.
This means that your desktop Mac, which really does not run server applications of any kind, is not at any serious risk.
As an end-user, it is recommended that is safer to await an official security update from Apple.


Question: what are the pros and cons of vim and emacs?

Response:
While both editors are powerful enough to handle any and all text editing needs–either one can do just about anything you can imagine, they have a similar footprint and they're both so customizable.
Vim gets good user reviews for the following characteristics: faster, good for quick, one-off tasks, more "Unixy" and sees itself as part of a greater tool-belt, is available on every unix system, is easier to use after some training, has good documentation and on-line help, works faster on slower machines and some report that almost all programming needs are taken care of from within Vim.
Some users, however, do not prefer vim because it's "modal".
Emacs is well-liked for the following reasons: it has considerably more extensions to let you do tasks that are only vaguely text-editor related, is easier to learn ("approachable") is available for every desktop/server,
features stay out of the way when not in use, has good documentation, is a great programming environment and some users see it as a "live in" editor that can be used continuously, seemingly built to keep you inside, making things "nice and comfortable so you don't have to leave".
But some find that Emacs has an odd habit of "pausing" for up to minute and becoming unresponsive, even while continuing to accept keyboard input, that starting a remote Emacs is often slower than starting a remote Vim and that it is not available for default installation.
Some users say that the main difference between Emacs and Vim is ergonomic, for example, in Vim you can edit text only with one finger, whereas in Emacs you can not–it's known to be "hard on your pinky fingers".


Question: looking for vnc client solutions that work reliably on a mac running os x 10.9.5

Response:
OS X is designed to work with the VNC protocol directly out of the box, enabling you to work with VNC connections.
Additionally, Real VNC is available as a free iOS app.
The built-in VNC client in OS X works effectively in connecting to most VNC servers.
TigerVNC is a recommended choice for use with OS X's VNC client due to its speed.
An alternative recommendation is that the built in Screen Sharing app which resides in System/Library/CoreServices can connect to most VNC servers and is slightly faster than other options such as RealVNC.
For connecting to remote Linux machines, Mac's native VNC client can be utilized, facilitating the setup through the "Connect to Server" option in Finder.


Question: do we really need oo languages to manage software complexity?

Response:
OO languages are not a strict requirement to manage software complexity, as alternatives like procedural programming can implement features such as code reuse and modularity.
However, OO languages provide strong benefits, such as binding functionality to data and promoting encapsulation and polymorphism, which some argue can enhance programmer productivity.
Despite this, some believe that OO languages can simplify tasks in many cases, especially when dealing with GUIs.
The core principle of OO, combining data and behavior, is a significant innovation that aids in managing complexity.
On the other hand, it's argued that non-OO languages, like C, can accomplish the same tasks through other means, such as function pointers for runtime modularity, and that OO languages mainly benefit novice programmers.


Question: what are rainbow tables and how are they used?

Response:
Rainbow Tables use a time-memory trade-off technique where you pre-hash all dictionary values instead of hashing each word on the fly.
They are useful for cracking strong passwords that cannot be easily found in a dictionary, and they work by creating a slow table and running multiple databases of hashes against it, which is faster.


Question: does tail read the whole file?

Response:
The command "tail" doesn't read the entire file from the start; instead, it seeks directly to the end and then reads in reverse to retrieve the specified number of lines.
It will correctly order the lines before displaying them up to the file's end.


Question: what does c++ do better than d?

Response:
One opinion offers that when programming in C++, you can attain complete control over your program, signifying total freedom to tweak and adjust intrinsic features such as memory allocation or the standard library to your specific needs.
What can be done in D is not particularly notable and doesn’t substantially outshine what C++ is already capable of, diminishing its attractiveness to C++ programmers.
Another opinion advises that D simplifies certain aspects by having just one casting operator whereas C++ has four, which can streamline some programming tasks but might lack the nuanced control found in C++.
D has far fewer implicit casts than C++ and is more likely to declare that two functions are in conflict with each other.
Another perspective is that C++ surpasses D in terms of quality like better compilers, tools,  more mature libraries, more bindings, more experts, more tutorials, etc.; basically, having a better variety of all the external elements to be expected from a more mature language.
Additionally, it is offered that the state of affairs is better in D and D disallows multi-root hierarchies but you cannot throw an int whereas you can in C++.
One opinion appreciates the ability in C++ to document a function argument or return value as a C++ reference instead of a pointer, hence implying taking a non-null value.
C++ is much better at forcing you to be verbose, which might be better or worse in your eyes, depending on whether you like inference or verbosity.
In D, value-type inheritance isn’t feasible, impacting the usage of RAII with stack memory.
Lastly, most important thing that C++ "does better" than D is interfacing with legacy libraries and benefits from having multiple independent vendors.


Question: my school wants to keep the details of our door authentication system a secret. is that a good idea?

Response:
Obscurity isn't a bad security measure to have in place.

However, some dispute that it is definitely a good thing, and say security by obscurity is bad on the grounds it may lead to complacency, but when obscurity is added as a layer on top of other controls, it can be absolutely legitimate.


Question: how to keep two versions of an app installed?

Response:
Attempting to install multiple versions of an app on Android is not feasible due to package name conflicts.
An alternative approach is to repackage the application with a different package name.
The process involves using a tool like apktool to modify the package name in the AndroidManifest.xml file and then signing the modified apk.
Another method suggests just changing the package name without the need for extensive tools or skills, using software like ApkRename and JAVA on a computer.


Question: what is the difference between process and job?

Response:
A process refers to any running program that operates within its own address space.
When we talk about a job in the context of a shell, it implies any program that is started interactively and continues running in the background or foreground, which is not detached like a daemon would be.


Question: where do i put my systemd unit file?

Response: You can put them all in /etc/systemd/system,  /etc/systemd/system/multi-user.target.wants/, /usr/lib/systemd/system, /usr/local/lib/systemd/system.


Question: what is the difference between https://google.com and https://encrypted.google.com?

Response:
The handling of referrer information for ad clicks differs between Google's services.
In July 2013, Google's two sites preferred different key exchange algorithms, with vanilla google.com using ECDHE_RSA and encrypted.google.com using ECDHE_ECDSA, both providing forward secrecy.
On January 16, 2017, the notable difference between Google's services was the absence of the Google Apps icon on the top right on encrypted.google.com, with both sites having comparable load balancing and using the same certificate.
Google stated in 2010 that encrypted searches through a named subdomain allowed organizations to filter and block encrypted searches they couldn't inspect.


Question: is plaid, a service which collects user’s banking login information, safe to use?

Response:
Plaid's security efforts have been criticized because they require users to give the company full access to a vast range of personal financial data, unlike other payment services that only need an account number.
Furthermore, Plaid may share this collected information with their clients with whom the user engages through their services.


Question: is bash in osx case-insensitive?

Response:
It's not a question of BASH's system, but rather the default file system on macOS: this system is case insensitive, meaning it typically does not differentiate between file names with varying capitalization.
MacOS's APFS file system, while case insensitive, preserves the case of file names.


Question: change the python3 default version in ubuntu

Response:
There are a number of approaches to changing the Python3 default version: one is to create a symlink for `/usr/bin/python3`.
An alternative way to change the simbolic link by `ln -sf python3.6 python3 inside /usr/bin`.
If you have multiple version of Python in your system, you can update the symbolic link of Python inside `/usr/bin/`.


Question: whats to stop someone from 3d print cloning a key?

Response:
The simple answer is absolutely nothing, other than honor, as sense of morality, knowing the difference between right and wrong, respect for other people, and their property, and when that fails, a .357 Magnum and a bad attitude usually suffices.

People without TV/Youtube may see nothing at all to stop them, but others will be aware of the cost; printing a key is a waste money and effort, when your average basic bump key set is cheaper, re-usable and works for 80% of the locks, or the locks can be picked, or bypassed entirely (go through the window).

If concerned about 3D printing, have a key/lock solution with atypical features, such as electronics or some interactivity that can't be replicated with your standard 3D printer.


Question: what does stage mean in git?

Response:
In the Git version control system, the term "stage" refers to the process of preparing a file for a commit.
Imagine staging as a dump truck ready to move the work you load into it.
This step, occurring before the commit process, is akin to a loading dock where you have control over the changes that will be shipped away.
When you stage a file, you meticulously prepare it, creating an intermediate step between completing your work and making a permanent commit to the repository.
It's essentially an unnamed, uncommented local commit that provides a transitional state in your local repository.


Question: why do we need a 3-way handshake? why not just 2-way?

Response:
A two way handshake would only allow one party to establish an ISN, and the other party to acknowledge it; while the three-way handshake is necessary because both parties need to synchronize their segment sequence numbers used during their transmission.

Logically there are four steps involved, but the second and the third steps (of the four) are combined, so technically there are three packet exchanges, and the real reason for using 3-way handshake is to avoid half-connections.


Question: how can i capture traffic on cisco ios switches?

Response: If your traffic happened to be passing through a router running Cisco IOS 12.4(20)T or greater, another possibility is to use the Embedded Packet Capture feature.


Question: why do we need to fork to create new processes?

Response:
The reason forking is a part of Unix is because it was relatively simple to implement within the existing system, mirroring the concept used in the Berkeley time-sharing system that was a predecessor to Unix.
Integration into Unix was facilitated due to the Berkeley system's capability to handle a rudimentary form of process control, and the initial set-up of forking didn't require extensive changes to that system.


Question: the slash after an ip address - cidr notation

Response: The slash following the IP address represents the bit length of the subnet mask, and is called Classless Inter-Domain Routing (CIDR) notation.


Question: is android showing app ads in share menu now?

Response:
Microsoft was reported to be misusing Android's share sheet by including advertisements to its applications with Reddit and Android Police links.
This activity is a breach of the policies regarding monetization and advertisements.


Question: android phone charging slowly: how to make it faster

Response:
To address a device that is charging slowly, one can increase the power supply by using a Type C port, especially if it supports Power Delivery for faster charging, or by connecting the device directly to a wall outlet rather than a computer.
Trying different USB cables can also be beneficial, as some cables and adapters are more efficient, depending on the device's model.
Another solution to a device charging slowly is diligently cleaning the charging port with compressed air, toothpicks, or other non-conductive items, but metal objects like staples, while effective, pose a higher risk and should be used with caution.


Question: do network switches have ip addresses?

Response:
While ip addresses are needed for switch management, using a public IPv4 address for switch management is wasteful use of a valuable and limited resource.
It is recommended not to assign management addresses to general VLANs but rather to use a dedicated VLAN for management, typically employing private IPv4 addresses.
In exceptionally large networks where even private IPv4 addresses might be considered scarce, the use of IPv6 for management could be contemplated, though the compatibility of hardware with IPv6 should be taken into consideration.


Question: are mozilla add ons safe?

Response:
Historically, the FAQ in April 2017 and earlier offered a reasonably strong guarantee of safety, providing users with a level of confidence that the add-ons should generally be safe to install.
However, instances of concern have been raised, particularly regarding add-ons in the Experimental category, where some have been discovered to contain malware.
This underscores the importance of exercising caution when installing add-ons, as there is a potential risk that they could harm your computer or compromise your privacy.
Despite these cautions, the consensus remains that, under normal circumstances, Mozilla add-ons should generally be safe to install.


Question: how to be notified when someone uses find my iphone?

Response: No, there is no way for them to know the device is being viewed through Find My iPhone.


Question: using the not equal operator for string comparison

Response:
When setting conditions in a script, combining multiple exclusion conditions with ANDs rather than ORs is recommended to achieve the desired control flow logic.
Using a switch or case statement might offer a more structured alternative for handling different values of a given variable, such as "PHONE_TYPE".


Question: is 4-5 years the “midlife crisis” for a programming career?

Response:
No, 4-5 years into a programming career doesn't signify a midlife crisis; rather, it marks the end of the honeymoon phase or a sign that you have reached a certain level in your career.
Conversely, some individuals agree it's a midlife crisis while others' personal experiences align with the notion that the feeling is not unique to any one person but is a common experience in the industry.


Question: is momentary physical access dangerous?

Response:
The potential actions of an attacker vary depending on the system, the attacker, and their preparation.
They could inject malicious code, use a keylogger, access files or physically damage the computer.
Other types of malicious actions go beyond hacking, including the use of USB devices that can destroy a computer, causing financial damage and downtime.
Furthermore, the risk spectrum includes numerous devices that are particularly dangerous within a very short timeframe.
For instance, malevolent FireWire devices or other technologies can be harnessed to directly penetrate RAM or utilize similar direct access strategies, pointing to the physical and security risks associated with peripheral ports.
This indicates the presence of sophisticated and diverse USB-based exploits, including deceiving devices that could conduct unauthorized actions or serve as pathways for further attacks.


Question: application level volume control in os x?

Response:
Jack, initially designed for GNU/Linux, is a low-latency audio server that likely includes volume adjustment capabilities.
SoundBunny, priced at $9.99, also offers this functionality.
Another discovery is volumemixer-app.com, a tool similar to the Windows counterpart.
For those seeking free and open-source solutions, BackgroundMusic is a viable choice.
If you have Xcode installed, BackgroundMusic is an option.
Finally, Rogue Amoeba's SoundSource utility stands out for its ability to precisely control application-level volumes and more.


Question: os x computer name not matching what shows on terminal

Response:
It's perfectly normal, because when you login Terminal remotely bash does a reverse DNS lookup.
It would only be the same if the reverse lookup failed to resolve, or if the hostname is not specified on the network you're connecting from and there is no reply from the DHCP server.


Question: how do i copy a folder keeping owners and permissions intact?

Response:
One can copy files while ensuring that permissions, ownership, and directory structure remain unchanged, using the command `tar cf - my_home | (cd /media/backup; sudo tar xf - )`.
The `cp` command also supports the preservation of file attributes with the option `-p`, which maintains modification time, access time, file flags, file mode, user ID, and group ID, according to the manual page.
Similarly, `sudo cp -rp` can be used to directly copy files from one location to another while preserving mode, ownership, and timestamps.
Another method involves using `sudo rsync -a', which nearly preserves everything, though it doesn't include hardlinks.
The command `cp -pdRx` is another alternative for preserving links, mode, ownership, and timestamps.
It's also noted that `cp` has a `-p` option specifically for preserving permissions.
If one prefers to copy directories exactly as they are, the `cp -a' option serves as a suitable method, retaining all file attributes and not dereferencing symlinks.
Lastly, one can use `cp -r --preserve=all` to ensure that all attributes like owner, group, and timestamp are kept intact during the backup process.


Question: what kinds of encryption are _not_ breakable via quantum computers?

Response:
In public key cryptography, three schemes are quantum-secure: Lattice based cryptography, like NTRUEncrypt, based on lattices; code-based cryptography, like McEliece cryptosystem, based on information theory; and multivariate cryptography, like Hidden Fields Equations.

Quantum computing will have the most dramatic impact on asymmetric encryption, but symmetric algorithms like AES are considered safe with a large enough key size (256 bits).


Question: how to properly use drag and drop with macbook pro on os x 10.7?

Response:
It is recommended to use your thumb to click on the lower part of the track and the index finger to move; then as long as you keep the trackpad pressed with the thumb, you can release the index finger.
An option for dragging is available by turning on the three fingers feature in trackpad preferences and one user believes that there used to be an option there called Click lock.
Moreover, another user advises that by using the three-finger drag, you can tap with three fingers and drag them across the trackpad, which allows for a delay in the action for repositioning your fingers.
Alternatively, you can enable a double tap feature for selecting and dragging without clicking in the accessibility settings.
The three finger drag is also available in the accessibility settings area.


Question: no partition scheme option when erasing a usb disk in macos high sierra?

Response:
You can resolve this by selecting "View" and then choosing "Show All Devices".
Afterward, select the actual drive you intend to reformat, and during the erase process, you should now have the option to choose a partition scheme.


Question: where is my whatsapp backup stored on icloud?

Response: In a hidden folder in the iCloud Drive, which you can find by typing a search term in Terminal.


Question: copy specific file type keeping the folder structure

Response:
To duplicate .csv files while maintaining their directory structure, you can utilize the combination of find and cpio in pass-through mode: '-name '*.csv' | cpio -pdm /target '.
Another approach for this task is using rsync: `$ rsync -a --prune-empty-dirs --include '*/' --include '*.csv' --exclude '*' source/ target/` or  `$ rsync -a --include '*/' --include '*.csv' --exclude '*' source/ target/` which keeps empty directories from the source tree.
The rsync manpage suggests using the -R or --relative option to replicate the entire directory path of the files.
Find command options include: `find . -name '*.csv' -exec cp --parents \{\} /target \;` and `find -name "*.csv" | xargs cp --parents -t /target`.


Question: hacker used picture upload to get php code into my site

Response:
If your app handles any sensitive information, I would highly recommend that you let someone with security experience have a look at it before you take it into production.

You should ensure that you're verifying the file on both the client and server, and it’s best to verify that both file location and file extension are used to define what PHP will process, and to segregate uploads and other untrusted content into locations and extensions that won't be processed.

Ensure that you don't have any other unpatched flaws on your server (for example, outdated plugins, exploitable servers, etc.).

You can't trust user data ever and must validate everything, but you can keep the image, if you make a resized copy of the original/uploaded file with PHP using GD or Imagick and use the new image, which will destroy any injected code.

You can disable PHP in your upload directory by using .htaccess to prevent the upload directory running PHP code.

You can use a white-list strategy to check for things you know are ok and reject everything else.

You can verify an image’s EXIF tags or use a strpos function to find a PHP code in image content.


Question: how can i reduce a videos size with ffmpeg?

Response:
For better compression, using H.265 instead of H.264, replace the libx264 codec with libx265 and increase the CRF value to achieve additional compression.
When choosing the libx265 codec, a reasonable CRF range might be between 24 to 30.
In the case of two-pass average bitrate encoding (2-pass ABR), you would typically update the libx264 video codec to the more efficient libx265 codec.
The -crf option is commonly utilized for x264 encoding, and choosing a CRF value around 23 can yield DVD quality.  Additionally, for compression without perceptible loss in quality, you could execute a default conversion using ffmpeg without specific options.
Among other methods to reduce video size, modifying the bitrate, varying the Constant Rate Factor, and changing the video screen size were tested.
Furthermore, for HD video compression with minor noticeable quality loss, a command with crf 28 and certain presets for faster encoding and specific tune options can be employed.
Lastly, to find the desired size reduction, running a script with a range of crf values could be helpful.


Question: what is the difference between screen sharing and remote management?

Response: With the El Capitan system, you have to configure Screen Sharing under Screen Sharing first, even if Remote Management is on, and then turn Remote Management back on again.


Question: how to delete photos from icloud but keep on computer?

Response: On your laptop, move your photos to a separate folder, then delete them from iCloud; on your phone, upload the photos to your laptop and delete them from the phone, then turn off photos in iCloud.


Question: difference between subnet and vlan?

Response: A VLAN is an Ethernet level concept, splitting it into multiple, logically separate Ethernet networks, and a subnet is an IP level concept; they partition different layers of the network model: subnets are Level 3 and VLANs are Level 2.


Question: what directory comparison tools can i use on os x?

Response:
Tools like Diffmerge, rsync, Beyond Compare and the Changes app are suitable for comparing directories in OS X, with the latter two being available for purchase.
Meld and FreeFileSync are recommended open-source tools that serve the same purpose.
Additionally, macOS and Linux users have a built-in utility that allows the use of the diff command to compare directories directly from the terminal.


Question: how do i write to ntfs drives in os x?

Response:
For Mac users seeking to enable NTFS support, the simplest solution would be to utilize MacFUSE and NTFS-3G for MacFUSE.
As of OS X 10.6, you can enable NTFS support natively.
For current solutions as of May 2015, free options include FUSE for OS X and building NTFS-3G from source or using Homebrew, while paid options include Paragon NTFS and Tuxera NTFS.
Some users may receive a free Paragon NTFS driver from certain hardware providers like Seagate.
For users comfortable with Terminal, they can manually enter commands to write to NTFS drives without needing to reboot.
This process involves identifying the disk identifier for the NTFS partition, unmounting, and mounting it with read-write permissions.
Another approach requires using Terminal to edit the fstab file to ensure the disk name label is one word and then creating a symbolic link for easier access.
For latest compatibility with OS versions from OS X 10.11 El Capitan through macOS 10.14 Mojave, installing the latest versions of osxfuse and NTFS-3G via Homebrew is recommended and requires temporary System Integrity Protection disabling.


Question: why use a database instead of just saving your data to disk?

Response:
Databases allow for efficient data querying, enabling users to ask questions and retrieve information rapidly.
They also enable the linkage of data from various tables.
This is particularly beneficial when dealing with relational data, such as customers purchasing products with connections to suppliers and manufacturers.
Databases are optimized to save just the things that change to disk in a fault-tolerant way.
Also, they are designed, so you can quickly just load the little bits of data you need at any given time.
Features like indexing of records and efficient transfer of information further contribute to the advantages of using databases.
Moreover, databases handle concurrent updates, transactions, caching, and asynchronous I/O, making them more correct and performant, while simultaneously simplifying code implementation.
They are essential when multiple processes modify data to avoid conflicting changes or when data exceeds memory capacity.
In addition to managing concurrency, reliability, and performance issues, databases allow programmers not to bother with how bytes and chars are represented in the memory.


Question: is apfs required for mojave?

Response: No, APFS is not required, though, yes, it can work as an alternative to HFS.


Question: what is certificate pinning?

Response:
The concept referred to involves solutions to issues in SSL certificate chain verification.
Certificate Pinning serves as a means to ignore the standard hierarchy of certificate trust by specifying to trust a certain certificate only, essentially disregarding other root CAs that might otherwise be considered trust anchors.
Additionally, it is a way for a server to state that this should not happen under normal conditions, and that the client should raise a metaphorical eyebrow should an unexpected certificate switch occur.
SSL pinning potentially adds an extra security layer from replay attacks in which the app will bundle the known server certificates with itself.
Finally, certificate pinning allows you to bypass standard certificate authority chains to mitigate the risk of an valid certificate be issued to a criminal.


Question: how to transfer files from pc to android emulator?

Response:
To transfer files to or from an SD card image when using an emulator, you should utilize the adb push command to copy files from your desktop to the emulator, and adb pull to copy in the opposite direction.
You can also make transfers using the DDMS UI, albeit only one file at a time.
First, in the Devices tab, select the emulator that you want to view the file system for, then locate the file in the File Explorer and click the Pull file button.
Finally, to copy a file to the device, click the Push file button on the File Explorer tab.


Question: how do i root my android device?

Response:
It is advised that rooting your device will probably void your warranty with both the carrier and the manufacturer.
It is important to note that there is no known method that will root all devices and no guarantee that any mentioned program or method will actually work.
The simplest way to root your device is via "one click" methods, most of which are developed for more popular devices.


Question: what does lc_all=c do?

Response:
It is assumed that ANSI-C might have defined the "POSIX" locale, which is related to the C default locale.
An application's output language defaults to the system's default when the LC_ALL environment variable is set to a particular locale.
The LC_ALL environment variable is paramount as it has the capability to override all other localization settings, except for $LANGUAGE, under specific conditions.


Question: changing creation date of a file

Response:
When changing the creation date of a file, the touch -t command typically modifies only the modification and access times, affecting the creation time only if the specified time is earlier than the original creation time.
For those looking to batch change the creation date of multiple files, a convenient solution involves using a simple Automator Workflow.


Question: whats using my gps?

Response:
Many apps use GPS functionality when it's switched on, and some apps, such as the camera, utilize it to embed location information into your photos.
Google employs GPS for various services, including Buzz, Maps, and Latitude; Latitude can intermittently update your location, which is a feature you agree to by using the service.
The device may also inform Google about nearby Wi-Fi spots and cell towers to enhance GPS efficiency, enabling quicker location locking.
To maintain privacy, it's advisable to deactivate GPS when not in use and scrutinize app permissions during installation—especially if an app like a cooking recipe app requests GPS access without a clear need.


Question: how can i display the current dns servers from the command line under os x?

Response:
The 'grep nameserver <(scutil --dns)' command is a useful command to list current DNS entries.
Moreover, to extract specific details for scripting purposes, you can employ a pipeline connecting to the 'awk '{print $3}' or 'grep -o "[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+\"' command.


Question: how to search the play store by permissions?

Response:
A simple answer to this query is that you don't need to take any action.
However, an alternative approach involves creating a Java application using the android-market-api.
As of the current situation, it's not possible to search applications on Google Play based on their permissions because doing so would require access to a database which Google API does not grant.
Nonetheless, there's no official solution provided; an unofficial workaround is to use a privately maintained database that enables search by permissions.
If these options don't suit your needs, you can try using AppBrain's API for a simple solution.


Question: confused by the many locations of the virtual /sdcard/

Response:
The change to /sdcard/0/ from /sdcard/ with the introduction of Android 4.2 Jelly Bean was due to the introduction of multi-user functionality.
These changes imply that the memory layout for the internal virtual SD card shifted to account for multiple users on a single device, with the path /storage/emulated/0/ representing the ownership by the initial user.
Additionally, it's noted that paths could vary for additional external devices connected to the system; for instance, another SD card or a USB device could lead to different mount points.


Question: how can i find a good open source project to join?

Response:
An effective approach to contributing to open-source projects is by selecting a project that genuinely interests you and one that you find yourself using regularly.
OpenHatch was specifically established to assist individuals in finding suitable open-source projects based on various criteria including type, technology, and skill level, helping you find a project that aligns with your abilities.


Question: i am missing the option to see the remaining battery life as time in the menubar?

Response:
One opinion advises that Apple deliberately removed the option to display remaining battery time in the menu bar on MacOS, and there are no indications that this feature will return.
Users seeking an alternative can find it in apps like SlimBatteryMonitor, which saves more space in your menu bar and lets you choose what information to show in specific states.
Another solution is the iStat Menus app, which offers a broad range of information beyond just battery stats.
A cheaper and simpler option is the app called Watts, which provides high configurability and includes features such as scheduling reminders and calibration for a modest cost.
Despite the change in MacOS Mountain Lion that removed the remaining battery time feature from the menu bar, a very simple app has been created to specifically show time remaining: Battery Time Remaining, and it replicates this function with an almost matching icon design and additional features.


Question: can i install android on my non-android device?

Response:
In theory, every device that satisfies the minimal conditions stipulated by Android can run the operating system; it simply involves tailoring Android to suit the specific device's architecture.
However, the implementation is constrained by the availability, or more commonly, the lack thereof, of firmware and hardware drivers, specifically their source code, which is seldom provided openly.
Without drivers engineered for the particular device, Android will not operate on that device.


Question: are there any risks to rooting a device?

Response:
Rooting a device comes with certain risks, including the potential to brick the device, although it should be unlikely, and it depends on how you do it.
Doing so often voids the warranty, especially outside the EU, where warranty terms are not upheld if the state voids it.
Updates from the manufacturer may stop if the device is rooted and a custom ROM is installed, or certain updates might unroot the device.
Rooted phones, however, can be as secure as unrooted ones if root permissions are managed correctly.
Rooting your phone inevitably involves granting root permissions, and the risk arises when apps with root access turn rogue or inadvertently share permissions, potentially allowing untrusted apps to gain similar access.
Therefore, it's crucial to be mindful of the apps to which you grant root access to ensure the security of your phone.
Moreover, there are instances where malware has escalated to root permissions on un-rooted phones as well.


Question: why does it matter that html and css are not programming languages?

Response: The distinction between what qualifies as a programming language and what does not with regard to HTML and CSS is not particularly significant.


Question: how to prevent command-i/command-shift-i from opening mac mail when in browser?

Response:
One approach offers that you can change the shortcuts from System Preferences.
The shortcut Cmnd+Shift+I in Chrome can be used to "Email the current page," but it may be frustrating due to its proximity to the developer tools shortcut.
One method to prevent this behavior in Safari is using FastScripts to map Command+I to an empty AppleScript.
Alternatively, in Chrome, you can disable Command+Shift+I by installing the Shortkeys extension and then opening the Shortkeys's preference panel, adding a command+shift+i shortcut and then Restart Chrome.
If you're using Better Touch Tool, it can also be used to override shortcuts.
Assigning a keyboard shortcut to activate an extension via chrome://extensions/shortcuts is another simple method.
Lastly, reassigning the problematic shortcut, (Cmd-Shift-I), to a different action, such as launching Developer Tools in Chrome or making a copy of the screen to the clipboard, can stop the Mail app from launching.


Question: how do i transfer edited photos from my iphone to my computer?

Response: AirDrop or email the photo to yourself, or, if you've enabled iCloud Photo Library, download it from the Photos web app at iCloud.com.


Question: where are systemd service logs?

Response:
For most distributions currently in use, the standard method to review the stdout and stderr of a systemd unit is via journalctl; to view them, one would execute a command like sudo journalctl -u followed by the name of the unit.
On Fedora systems, such logs are typically found at the /var/log/messages directory.


Question: how can i make cron run a job right now, for testing/debugging? without changing the schedule!

Response:
Cron has a special purpose–running schedules commands at a specific time–so the best thing is to either to manually create a (temporary) crontab entry or write a script which removes and resets the environment.
To simulate the cron user environment, you can follow a two-step process: writing a temporary line in the crontab `* * * * * /usr/bin/env > /home/username/tmp/cron-env` and then using a bash script `#!/bin/bash /usr/bin/env -i $(cat /home/username/tmp/cron-env) "$@" `.
Additionally, you can force a crontab to run immediately by using the following command: run-parts /etc/cron.daily.


Question: is exploit-free software possible?

Response:
Creating exploit-free code is a challenging process that becomes more complex with increasing software complexity.
Producing high-quality code devoid of vulnerabilities is possible, yet doing so would require substantially more resources.
While concepts of exploit-proof software are theoretically feasible, the economic and practical limitations make them currently out of reach.
However, in the distant future, there is some hope to make it eventually possible to write exploit-free code as long as all the used algorithms are provable.
The prevailing software development environment, which includes performance priorities and fundamental system flaws, makes the likelihood of exploit-free code in the near future quite slim.
Nonetheless, small and trivial software has the potential to be without bugs or exploits, as their simplicity allows for a more predictable and secure response to any inputs.
Even though creating entirely secure software is feasible, the absence of necessary economic incentives and regulations significantly hinders its realization.
If the security of a software system is mathematically validated, the potential for exploit-free software exists, although such efforts are rare and complex.
While proving software correctness through mathematical proofs is possible, there are hurdles, like hardware vulnerabilities and unpredictable environmental factors, that must be addressed.
Software can technically be free of exploits, highlighting the utmost importance of the mathematical foundation behind it, despite the inherent difficulties.
Lastly, while it is possible for specific cases (programs) to be almost exploit-free, this is not the case in general.


Question: homebrew: rollback from python 3.7 to python 3.6.5.x?

Response:
If you still have the previous Python version installed, you can easily switch using the command `brew switch python 3.6.5_1`.
In case you don't have the earlier version available, you can install Python 3.6.5_1 from the previous formula by using the appropriate command.
Another approach is to execute `brew switch python 3.x.x_x` where you replace '3.x.x_x' with the specific version you want to switch to, for example, '3.6.5_1'.
Alternatively, if you are using the ASDF version manager, you can unlink the current version with `brew unlink python`, add the Python plugin with `asdf plugin-add python`, install Python 3.6.9 with `asdf install python 3.6.9`, and set it as the global version with `asdf global python 3.6.9`.


Question: why are tar archive formats switching to xz compression to replace bzip2 and what about gzip?

Response: Xz is considered more efficient in terms of compression ratio, thus saving disk space and optimizing the transfer through the network.


Question: how do i remotely edit files via ssh?

Response: You can do so by mounting the remote folder as a file-system using sshfs.


Question: how can i start the python simplehttpserver on port 80?

Response:
To initiate the SimpleHTTPServer using Python, you could employ the command "sudo python -m" followed by "SimpleHTTPServer 80" for Python versions before 3.x, and for Python 3.x or later, "sudo python -m http.server 80" should be used.
However, ports below 1024 require root privileges and, this practice can expose your system to security risks.
An alternative command to start a server without needing root access involves specifying a higher port number, for instance, "python -m SimpleHTTPServer 50505", where "50505" represents the port.


Question: how do i create my own programming language and a compiler for it

Response:
Firstly, you'll need the right educational background; go to college and specialize in software engineering and taking every compiler class possible.
You'll also want to stick with math classes throughout high school and your 4 years in college, focusing on non-standard math topics (logics, group theory, meta-mathematics) in order to help you think abstractly.
Also, expose yourself to as many good programming languages as possible.
Starting with machine code and progressing to more complex languages, one could write a simple assembler first, then use it to create a compiler for a simpler form of C, eventually advancing to develop more intricate languages.
Also, simpler assembly languages like the PDP-8 or "mix" can help to demystify the complexity of computers and programming.
Learning languages such as Python or Ruby, which have well-documented, open-source implementations, helps to understand various features and paradigms in programming.
Tools like ANTLR, a language generating framework, can provide a good starting point for those new to compiler construction.
When considering the design of your own language, reflect on the deficiencies of existing ones and think about solutions within a domain you are familiar with, which could lead to the creation of a domain-specific language.
Creating your own grammar is a fundamental step in compiler construction, much like the grammar rules of any language; you can then follow these syntax rules to translate your code into machine code or another intermediate form.
When it comes to creating compilers, it is key to remember that both the source and target languages need to be well-defined and specific; this can apply to any form of language, not just programming languages.
By learning how to parse and interpret these languages, you create a compiler.
To grasp the fundamentals of computer operation, it’s essential to understand the architecture of a processor, the role of memory, and the function of interrupts that facilitate input/output processes.
Every program, including compilers, essentially functions in three basic phases: reading input, processing it, and then writing the corresponding output.
In the realm of programming languages and compilers, it is important to break down complex problems into manageable parts, then write code line by line and rigorously test the resulting software.
Engaging in a concrete project and experimenting with it will integrate the theory behind compilers and actual practice.
Furthermore, actually doing will help you gain a better grasp of concepts compared to just theory.
Practical steps in compiling include reading a text file and extracting information which you then use to perform transformations until the desired machine-readable format is achieved.
Additionally, using simulators to construct a complete computer system from scratch can be a very comprehensive and practical way to learn the entire process from fundamental principles.
For an introduction to assembly-level programming, writing an X86 assembler in Linux that supports a subset of standard X86 assembly is a practical project that will deepen your understanding.
For writing an assembler, begin by crafting an interpreted language, then translate your language into another one such as JavaScript or a lower-level language like C (the lingua franca) or Assembly.


Question: does bcrypt have a maximum password length?

Response: Yes, BCrypt has an upper limit of 72 characters.


Question: where can i download safari for windows?

Response:
Apple has officially ended support for Safari on Windows and discontinued it.
Hence, in your case, it's recommendable to utilize a cross-browser testing tool to test your project.
However, while it is no longer updated, Safari 5.1.7 for Windows can still be found for download from various sources including the official Apple download page and archive websites, such as wordsoftech.


Question: how do i set os x to boot by default?

Response:
It is possible to set the default boot disk in System Preferences>Startup Disk.
Alternatively, if you press and hold the Control key while selecting the desired boot device during startup, this choice will be saved in the Startup Disk preferences, ensuring it remains set for future reboots.


Question: what does rc in .bashrc stand for?

Response:
The term "rc" in the context of computing and script files such as those in Unix originates from "runcom".
The "rc" in startup script names like /etc/rc or in configuration files like bashrc signifies "run commands", which are instructions executed automatically at system startup.
However, over time, the interpretation has expanded to "run control" as a convention, denoting files that control or configure initialization and setup of applications or systems.
Despite "runcom" being the historical origin, in modern usage, "rc" files are understood more broadly as "run configuration" and may contain various settings, not limited to executable commands, as seen in the ".vuerc" file used by the Vue.js framework's CLI, which is a JSON file.


Question: whats the canonical retort to its open source, submit a patch?

Response:
In response to "it's open source, submit a patch", you don't have to say anything, as developers are typically aware of issues affecting their users.
Some say there is no reasonable retort that will make any difference.
It's more constructive to offer collaboration, such as stating, "If you do it, I will include it," rather than dismissively responding with a "no".
However, if you're not in a position to contribute to the work yourself, it's advisable to privately share your circumstances with the project maintainer rather than seek solutions from an open-source community when you do not intend to contribute.
A polite yet firm response to rude suggestions like "submit a patch" is either to explain that the individual is being impolite or to cease the conversation with them.
In some situations, if confronting a skill mismatch, it might be appropriate to convey that a task is beyond your capabilities by saying, "There is no way I can do it as fast and well as you can" or "I don't have the skills, experience or time required".
Alternatively, initiating a dialogue about the broader value of your feature to the community could influence their decision to reconsider its implementation.
Still, if a suggestion or bug report receives an unwelcoming response or no response at all, sometimes the most effective course of action is to discontinue the use of the software.
You could also fork the project or switch to a well-maintained alternative.
Other possibilities include "thanks for the response," or "submit a patch".


Question: what is the difference between two step verification and two factor authentication?

Response:
Simply put, every two-factor authentication is a two-step authentication, but not the other way around.
However, from an information-theory point of view, there isn't any difference between them.
It is argued by some that two-step is just a layperson-friendly name for two-factor authentication.
However, in more technical terms, the difference is addition versus multiplication.
Two-step is an additive process in which you authenticate once with one independent credential, and then again with another independent credential.
Two-factor is multiplicative, in that you combining one independent credential with another to derive a stronger single credential than each independent one.
Furthermore, two-factor authentication must involve two different types of authentication categories, while two-step involves two types from the same category, like two passwords, two physical keys, two forms of bio-metric identification.


Question: single application not showing up in spotlight

Response:
When apps are transferred to a new Mac and don't appear as expected, it can be due to extended attributes (xattr) related to the macOS Finder's copy functions, including those that indicate ongoing copy progress: if this is why Spotlight isn't displaying the apps, you have to manually remove these extended attributes via Terminal commands.
Alternatively, a simpler resolution involves adjusting Spotlight's settings within System Preferences by deselecting and then reselecting the "Applications" checkbox; you may need to close and reopen "System Preferences" during this process.


Question: file open dialog is missing sidebar items

Response:
Open a Finder window; while in a open file or save as dialog box, you can drag folders onto the sidebar, and they’ll appear under a badly-named “Favorites” section.
If you go to Finder -> Preferences -> Sidebar and put a check next to all your Favorites, this should work.


Question: is it dangerous to post my mac address publicly?

Response:
No, disclosing the MAC address in itself shouldn't be a problem, as it’s unlikely in most cases that disclosing your Mac address will pose any threat to your security, or any direct risk to you as a person, unless you're trying to remain anonymous.

There are some theoretical hazards, but in practice, anyone in a situation to exploit them has other ways to get your MAC address.

One theoretical scenario is if someone knew you MAC address when you were connected to a public Wi-Fi network with a paid subscription for internet access, someone disguising themselves with you MAC address would gain internet access at your expense, and the traffic will appear to come from your computer.

Some Belkin routers set a default WPA password that could easily be derived from the router’s MAC address, so if the default isn’t changed, publishing your MAC address is an obvious security risk, because you’re effectively publishing your WPA password.

A MAC leak can reveal information about a server and, in a reported case, when a server was changed someone outside the organization became aware, and questioned the organization, causing worries about the possibility the server had been hacked, so in that sense it is dangerous.


Question: error opening a zip file: no such file or directory?

Response:
If you encounter issues with a zip file, it is advisable to reacquire the file by re-downloading or re-copying it from the original source and attempt to open it again.
Should the file still appear problematic, then it's likely that filename.zip is either not actually a .zip file, or is corrupted.
Checking if the file is genuinely a zip file through the terminal can help determine if the file is valid, and using commands to repair permissions and unzip the file can potentially resolve issues.


Question: how do mobile carriers know video resolution over https connections?

Response:
When it comes to streaming video, it is crucial to have consistent bandwidth to maintain stream quality, and to manage this, streaming sources mark their data packets to signal to carriers that the content is streaming video.
Additionally, a technology known as Dynamic Adaptive Streaming over HTTP (DASH) is often utilized, which adjusts the video quality in real-time based on the available bandwidth to ensure continuous playback without buffering.


Question: is there a way to look inside and modify an adb backup created file?

Response: Technically, you can extract specific data from an Android backup file, provided that you understand the requisite knowledge from the Android source code.