Question: why igp is used in mpls?

Response:
An IGP exchanges routing prefixes between gateways/routers.
Without a routing protocol, you'd have to configure each route on every router and you'd have no dynamic updates when routes change because of link failures.
Futhermore, within an MPLS network, an IGP is vital for advertising the internal topology and ensuring connectivity for MP-BGP inside the network.


Question: how do you achieve a numeric versioning scheme with git?

Response:
Take a look at the process of using 'git-describe' by way of GIT-VERSION-GEN and how you can add this via your build process when you tag your release.
For guidance, can also refer to the provided blog at http://cd34.com/blog/programming/using-git-to-generate-an-automatic-version-number/.


Question: why are my text messages coming up as maybe?

Response:
This is part of the Proactivity features new with iOS 9: It looks at info in emails to see if anyone with this number sent you an email and if it finds the phone number associated with a contact from your email, it will show you "Maybe".

However, it has been suggested there is a bug in iOS 11.2 that can result in "Maybe" being displayed even when "Find Contacts in Other Apps" is disabled.


Question: what is the difference between man and help in linux?

Response: "Help" is a Bash built-in command designed to provide assistance specifically for Bash commands, whereas "man" (manual) is a conventional way to get help for nearly all system commands and, occasionally, configuration files.


Question: chroot jail - what is it and how do i use it?

Response: A chroot jail is a way to isolate a process that does not run as a root and its children from the rest of the system; you must create a directory tree where you copy or link in all the system files needed for a process to run.


Question: are there any famous one-man-army programmers?

Response:
Bill Joy is notable for writing vi, among other programs, including csh, rlogin, rsh, and rcp.
Chris Sawyer was instrumental in creating RollerCoaster Tycoon, contributing to the game's programming, which included a physics engine, and writing it in assembly language.
Oren Eini, also known as Ayende Rahien, is the author behind Rhino Mocks and is known for writing elegant code.
Guido van Rossum created Python.
Richard M. Stallman, often referred to as RMS, created Emacs and gcc and is recognized for maintaining pace with commercial Lisp machine code.
The first version of Lisp can be attributed to John McCarthy.
Jamie Zawinski is associated with one of computer science's most epic stories.
Derek Smart was known for his involvement with Battlecruiser 3000AD and his penchant for flame wars.
Steve Wozniak was essentially Apple's early programming staff.
John Carmack created the engines for several iconic games, including the Doom, Wolfenstein and Quake series.
Ada Lovelace is celebrated as a pioneering figure in computing history.
Khaled Mardam-Bey is the author of the popular IRC client, mIRC.
The invention and first implementation of C++ is credited to Bjarne Stroustrup.
Jon Van Caneghem single-handedly wrote, designed, and developed the original Might and Magic game, with some assistance for artwork, Dan Bunten created M.U.L.E., Seven Cities of Gold and a variety of other games, and Bill Budge - Created Pinball Construction Set, alongside many other games, from scratch, by himself.
Shaun Inman is recognized as a solo developer.
Andrew Braybrook, Archer MacLean, Martin Walker, Jon Hare/Chris Yates, and Stavros Fasoulas are remembered for their individual contributions to Commodore 64 games, often doing everything themselves, including coding, sound, music, and graphics.
Larry Wall is known for creating Perl.
Matthew Smith is credited with writing Manic Miner and Jet Set Willy by himself.
Apple Writer was among Paul Lutus' creations.
Richard Greenblatt has made significant contributions at the MIT AI Lab, including developing a chess program and Lisp Machine.
Wayne Ratliff, the creator behind the dBASE software, coded it in assembler.
Nick Bradbury is notable for developing HomeSite, TopStyle, and FeedDemon, paying great attention to user feedback.
Highlights in programming language development include John Backus with Fortran, Stephen Wolfram for the Mathematica package, Tim Berners-Lee - inventor of World Wide Web and Phil Zimmermann - PGP.
Chuck Moore achieved recognition for creating Forth, as well as designing microprocessors and securing hardware patents.
Simon Tatham wrote the widely used SSH client, PuTTY.
Anders Hejlsberg is the creator behind Turbo Pascal, Delphi, and C#.
Cleve Moler is known for originating MATLAB.
Bram Cohen's project contributes significantly to internet traffic.
Markus Frind is the CEO of Plentyoffish.com, which he created alone, and the site generates significant revenue.
Jonathan Blow single-handedly developed the game Braid, including its sophisticated audio and particle systems.
D.J. Bernstein is remembered for qmail, djbdns, and his legal challenge enabling the publication of cryptography tools on the internet.
Charles Babbage conceptualized the idea of a programmable computer.
Phil Katz developed the important file compression utility PKZip.
Gary Kildall created CP/M, an early operating system.
Fabrice Bellard is recognized for writing FFmpeg, leading the QEMU project, discovering fast algorithms for calculating pi and FFmpeg and qemu, .
The hacker dark_alex falls into the one-man-army category.
Slava Pestov created the advanced programming language Factor and developed Jedit at a young age.
Jon Tackabury's contributions come from Binary Fortress.
Doug Cutting initiated the creation of Lucene, Nutch, and later Hadoop.
Contributions by Eugene Roshal include the FAR file manager, RAR file format, and WinRAR file archiver, while Mark Zuckerberg created Facebook.
Rich Hickey authored Clojure.
Scawen Roberts, recognized for his work on the game Live for Speed, has been programming it single-handedly for years.
Ogre3D, an object-oriented graphics rendering engine, was created by Steve Streeting.
Jim Kent's coding efforts were pivotal in the public release of the Human Genome Project's map.
Among renowned hackers, Eric Corley and Kevin Mitnick are acknowledged.
Wayne Venables allegedly wrote Fruitshow forum software in 3 hours.
Arthur Whitney developed the "K" programming language and implemented a compact SQL engine in it.
The creators of the Leisure Suit Larry series, SimCity, and Elite are Al Lowe, Will Wright, and David Braben, respectively.
jQuery, a popular JavaScript framework, was created by John Resig.
The original FruityLoops software was developed by Didier Dambrin using Delphi.
Sid Meier Co-founded Microprose and wrote Sid Meier's Alpha Centauri, and Sid Meier's Colonization, Sid Meier's Civilization IV.
Walter Bright worked solo on Digital Mars' C++ compiler for several years and initiated the D language.
Shawn Fanning is the creator behind Napster.
The creation of the Spring framework is attributable to Rod Johnson.
Peldi Guilizzoni developed Balsamiq, a tool for creating mockups.
Nasir Gebelli stands out for his early Apple II games like Gorgon and Space Eggs.
The near entirety of VIM was written by Bram Moolenaar.
Simon Peyton Jones is known for his research in functional programming and for authoring the Glasgow Haskell Compiler.
Wil Shipley's work includes Delicious Library.
Joe Hewitt created Firebug and DOM Inspector.
Kernighan, Ritchie, and others like James Clark and Audrey Tang have made notable contributions.
Donald Knuth and Ken Thompson are mentioned for their influence on programming.
Ken Silverman developed the Build engine for video games.
John Carmack, Dave Cutler, and others like Tim Sweeney are highlighted for major contributions to software and operating systems.
Paul Lutus is acknowledged as the father of Apple Writer.
Peter Blum developed a comprehensive collection of ASP.NET controls.
Matt Mullenweg created influential web development tools like WordPress.
Gus Mueller is recognized for his work.
Alan Turing, the father of modern computer science, is mentioned for his contributions.
Jordan Mechner programmed the original Prince of Persia games, and the animations were based on his brother's movements.
D. Richard Hipp is known for SQLite and other TCL/TK-related work.
Mike Pall wrote LuaJIT, while Julian Seward created bzip2 and Valgrind.
Markus Persson, also known as Notch, is known for developing Minecraft.
Bill Atkinson wrote MacPaint for the original Macintosh.
Again, Nick Bradbury is acknowledged for creating HomeSite, TopStyle, and FeedDemon.
Avery Lee developed Virtualdub, and Gabest was involved with Media Player Classic.
Jeff Minter, long-time video game programmer, created Tempest 3000 in assembler.
Austin Meyer is credited with developing X-Plane.
Justin Frankel created Winamp and Gnutella.
Markus Persson single-handedly worked on the design, programming, and graphics of Minecraft.
Dave Cutler was the father of VMS and NT and significantly contributed to Windows Azure.
Eddie Kohler is recognized for the Click modular router.
L. Peter Deutsch is recognized for Ghostscript and other works.
Charles Simonyi (Microsoft Word and Excel),  Joe Armstrong (Erlang) and Bertrand Meyer (Eiffel).
Ivan Sutherland's invention of Sketchpad is a significant milestone.
Cave Story, a game created by Daisuke Amaya, also known as Pixel, is celebrated.
Allan Odgaard is the author of TextMate.
Jeff Atwood is credited with creating the platform used for these discussions.
Dan Bricklin, inventor of the electronic spreadsheet, and Richard Bartle, for inventing MUD, are recognized for their pioneering work.
Andrew Tridgell developed rsync & samba.


Question: how do i disable the minimize (command-m) shortcut in mavericks?

Response:
To disable the Minimize (Command-M) shortcut in Mavericks, one approach is to install a key remapper, such as KeyRemap4MacBook.
Alternatively, you can adjust settings directly without additional software by going to System Preferences > Keyboard > Shortcuts > App Shortcuts and assigning a less likely-to-be-used combination for the "Minimize" and "Minimize All" functions.
In macOS 10.12 (Sierra), setting the CMD-M mapping to a different action works right away: the method involves going to System Preferences > Keyboard > Shortcuts > App Shortcuts, checking off the Show Help Menu item, and assigning it a Command-M key combination.
If you're using Karabiner with High Sierra or higher, you can create a configuration file to customize shortcuts.


Question: how can i move files and view the progress (e.g. with a progress bar)?

Response:
In order to build a patched cp and mv, you can create versions that support the -g switch to show progress available online 9`$ sudo cp src/cp /usr/bin/cp $ sudo cp src/mv /usr/bin/mv `), but one user prefers `$ sudo cp src/cp /usr/local/bin/cpg $ sudo cp src/mv /usr/local/bin/mvg` because it doesn't overwrite coreutils or break scripts in case of a problem.
Rsync is another tool that can copy files with a progress bar when using the -P switch, so if you have rsync installed and you could use a simple alias in your shell's dotfile: `alias cp='rsync -aP'` or `rsync -aP --remove-source-files $src $dst && rm -r $src` and you can use a shell script to create a progress bar during file copying.
The latest version of rsync has an alternate flag `--info=progress2` that shows progress for the entire operation.
The pipe viewer command pv allows you to show a progress bar when copying files, as does Midnight Commander (mc).
A tool named progress can find descriptors related to running commands to show progress and speed (`progress -w` outputs the stats for all running cp,mv etc. operations).
Gcp (Goffi's CoPier) offers an alternative method to add a progress bar without patching core utilities.
On Mint, you can use gcp (gcp SOURCE DESTINATION) or curl to transfer files with progress information.
By sending a SIGINFO to mv using CTRL-T, you will send a SIGINFO to mv, and can then get a report on the progress of the transfer.
Pv is another tool you can use to print progress based on line count or file count (You will need pipe viewer: http://www.ivarch.com/programs/pv.shtml mv -v sourcedir targetdir | pv -l -s filecount > logfile ) and combined with mv -v, it can give progress updates, use `find sourcedir | wc -l` to get file count.
Simply checking the size of the directory (`du -hs /directory/you're/moving/data/to`) can provide a way to monitor progress.
Finally, bash script `#!/usr/bin/env bash rsync -aP --remove-source-files "$@" && rm -rf "${@:1:$#-1}"` handles more then one source and filenames with whitespaces: `$ rsmv source1 source2 source\ 3 "source 4" dest`.


Question: how do i delete photos from my ipad but not icloud?

Response:
If you have iCloud Photo Library turned on, all of your devices' camera rolls are identical so, unfortunately, you cannot delete photos from your iPad, but not iCloud.

You can turn off iCloud Photo Library on a single device by following these steps: on your iPad, go to Settings > iCloud > Photos and turn off iCloud Photo Library, which will delete your photos from your iPad, but not your iPhone or iCloud account.


Question: can i make a song from itunes my ringtone?

Response: Yes, if you create a version no longer than 30 seconds in iTunes first, change the file name from .m4a to .m4r, then import it as ringtone, which you can then sync to your iPhone.


Question: how to disable battery full notification sound?

Response:
Currently, there is no built-in option provided to disable the "Battery Full" notification alert on certain devices, including specific Samsung models.
Nevertheless, you can adjust the global notifications to silent to prevent the alert from making a sound, yet this requires individually setting the notification tone for each app and doesn't serve as a perfect fix.
Alternatively, for those who need to mute their phone during the night but still wish to receive emergency calls, an app like "Night Ringer Free" can be utilized to create a whitelist for calls and messages while silencing other notifications.
There are also apps like Sound Manager that allow for scheduling sound volumes and types, enabling users to mute the notification volume during specific hours without affecting the ring or media volumes.
For users who are comfortable with using more advanced tools, Tasker is a solution on some devices that enables disabling notifications during a set timeframe, such as during the overnight charging period.
Moreover, some users have found that operating system updates have naturally resolved the issue, as noticed with the upgrade from Android 2.2 to 2.3 on the Samsung Galaxy SGS.
Finally, there are dedicated software modifications available separately for Lollipop, KitKat, and Jelly Bean, such as the 'GravityBox' Xposed module or the Disable Battery Full Alert module, which offer the option to remove the "Battery Full" notification sound.


Question: are no caller id calls dangerous?

Response:
Unidentified calls don't seem to present a significant risk.
However, you should keep interaction to a minimum, if you take such a call.
Scammers are experts at getting people to engage in order to trick them into a scam, so saying absolutely nothing is also an option.
However, sometimes legitimate companies have proper reasons for hiding their number.
If this is the case, you can always terminate the call and phone the company in question back via their phone number, which should be available on their website.


Question: how to get the hand tool back in preview.app in 10.8?

Response:
It is advised that the hand tool is still available when opening PDFs in Safari (in embedded mode).
Use the move tool by pressing ⌥ Option+Space.


Question: how to see full log from systemctl status service?

Response:
To see the full log from systemctl status for a service, you can utilize the journalctl command in various ways.
For a comprehensive log, use the following command: journalctl -u service-name.service.
Another option to include the complete output of the status listing without truncation is by adding the -l flag to the systemctl command: systemctl -l status service-name.
If you want to redirect the log messages to a file, you can use the command: journalctl -u service-name.service > file_name.txt.
Additionally, it is convenient and easy to use the following bash command: journalctl -xefu service-name.service or journalctl -xefu service-name.


Question: what is the purpose of using shift in shell scripts?

Response:
Shift is a bash built-in which removes arguments from the beginning of the argument list.
Specifically, shift alters the positional parameters so that each argument (e.g., $1, $2, etc.) moves down one position in the sequence; $1 gets the value of $2, $2 gets the value of $3, and so forth, while the original $1 is discarded.
Shift enables extraction of the complete value of the location (otherwise this value could get arbitrarily long) and allows the retrieval of all remaining arguments from the $@ variable after the shift operation is performed.
Moreover, shift operates in a First-In-First-Out (FIFO) queue fashion, comparable to the popleft operation on an array in high-level programming languages.


Question: how can i tell what version of linux im using?

Response:
The uname command is a useful tool to consider when managing a diverse array of machines.
You can obtain all necessary details by typing "uname -a" in the command line.
For a more focused approach, the manual page "man uname" provides a way to narrow down the information.


Question: how do i disable the click sound on the camera app?

Response:
To delete the camera sound file on your device, administrative access, known as root, is required.
For devices like the Nexus One, turning the system volume down via normal volume controls while in the camera may also silence the shutter sound.
Some users prefer using a specialized app such as Silent Camera to avoid camera shutter noises.
Additionally, certain camera applications may include a built-in option to disable the shutter sound.
This feature isn't exclusive to newer versions like Froyo; it's also found in older versions like Eclair on devices such as the Samsung Vibrant, within the camera's settings under a "Shutter sound" option.
For those utilizing automation apps like Tasker, a task can be programmed to set the system volume to zero whenever the camera app is launched, restoring the volume to its original state upon exiting the app.


Question: why is using a shell loop to process text considered bad practice?

Response:
One user indicates that performing text manipulation directly in the shell is considered to be inefficient and slow due to the shell's focus on file and file name management rather than file content.
Moreover, another user offers that this inefficiency is especially noticeable when processing large files in a shell loop, which can turn into a time-consuming task as even milliseconds per line can add up when dealing with thousands or millions of lines.


Question: how to show hidden files and folders in finder?

Response:
The command 'defaults write com.apple.finder AppleShowAllFiles true' followed by 'killall Finder' will show these files, and replacing 'true' with 'false' will revert this setting.
Alternatively, tools like the hiddenfiles widget or third-party software like Deeper or TinkerTool can assist.
Furthermore, to customize this behavior in Finder without third-party tools, you can execute similar commands in Terminal, substituting 'YES' or 'NO' in the place of 'true' or 'false' accordingly.
For a quicker method, press Command+Shift+. (period) in Finder to toggle the visibility of hidden files and folders.


Question: defence methods against tailgating

Response:
This is not a problem that has a social solution, you have to protect yourself by having a physical gate with a badge readers, and politely challenging people who are trying to get in without using the controls, by asking to see their pass or offering to escort them to reception/security, and if they resist, monitoring them and quietly informing security.

Without a physical gate, you put up scary “no tailgating - everyone must badge in at this door" signs, but also rule-compliant people to enforce the rule on their peers or strangers, so can request all employees challenge tailgaters.

Where it really matters, have controls posts and ID verification, and station a security person at every entrance whose entire job is to challenge people; also, make sure there are obvious cameras in the vicinity, including to do spot checks on the guards, and "secret drills" where someone tries to get in without a badge.

Receptionists should vet everyone who comes into the building notifying them that they must sign in before entering the building and ask them about the details about why they are there, while keeping records of entrances/exits, perhaps including a people counter.

If someone is tailgating you, use the 'U-turn and wait' method to see if the person behind has credentials to get through a locked door.

If you use airlock style doors, where someone has to pass through two doors, but cannot be followed through the first door, you will stop tailgating.


Question: combined `mkdir` and `cd`?

Response:
The commands `eval {mkdir,cd}\ FOLDER\;` and `mkdir foo && cd "$_"` provide methods for script or command line usage to create and immediately navigate into a directory.
The use of `$_`, a special parameter, after a command references the last argument from the previous command, aiding in streamlining the navigation process.
Double quotes are necessary around `$_` in certain shells, such as bash, to ensure the correct handling of directory names that contain spaces.


Question: does dd copy empty space?

Response: Using the "dd" command in Linux creates a bit-for-bit copy of a drive, capturing all the content, including "empty space," the blocks that do not officially contain data, partition information, UUIDs, and so forth.


Question: how can someone go off-web, and anonymise themselves after a life online?

Response:
It is not really possible to remove yourself entirely because the web is like a big memory that cannot forget.
Anything you ever wrote or published on the internet is there forever; trying to remove it is futile.
Most services, including Facebook and Google, do not permit removal at all and, even if some do, it is just a declaration because they merely hide that data.
A recent development in this area is that the European Court of Justice backed "a right to be forgotten" in a case against Google.
One option you have is to make it so confusing (use misinformation) that it becomes difficult for anyone to connect the dots.
Change your identity, country (to one where records are not systematically processed) and life pattern, and then try not to be discovered.
Entirely change your name, behavior, appearance, your country, and your friends so there is no correlation between data prior to the change and post-change.
You can also deliberately poison the results of any data analysis by making random or deliberately wrong choices on a significant number of your daily activities.
Naturally, it helps to reduce the signature you leave around to begin with, e.g. use cash, don't leave pictures online.
Another option is to become a hermit living near the pole of inaccessibility in Africa for the next 10 years.
Basically, if you want to stay anonymous on the internet, log off.


Question: xkcd #936: short complex password, or long dictionary passphrase?

Response:
In practice, long passwords tend to decrease security due to the challenges they present to users.
A long password composed of random words provides robust security, provided that the words are chosen entirely at random.
Generally, favoring length over complexity is recommended, but it is crucial also to consider the total entropy desired when creating passwords.
Some users say that in the length vs complexity debate, it is a wash because each would offer a similar level of protection.
However, entropy significantly decreases when users attempt to create memorable or logical sentences from random word combinations.
Some say that the number of words in a passphrase is more crucial than its length; dictionary attacks can be highly effective if the words are common and short.
In looking at several examples, one user believes that additional complexity should be enforced for shorter passwords, but longer passwords can be all lowercase if they exceed a certain character count, such as 20.
The difficulty of remembering a password is just as significant as its guessability, highlighting the importance of balancing security with usability.
Four-word passwords are advantageous because users are more likely to remember them without resorting to insecure practices like writing them down.
Diceware-type passwords are ideal for accounts accessed occasionally, but shorter passwords generated from random strings can be equally memorable for daily use.
Instead of forcing complex character combinations, password validation should check against dictionary and brute force attacks to ensure strength.
The Openwall Linux pwqgen tool generates secure passwords using entropy, avoiding spaces and instead utilizing punctuation and digits for word separation.
Long, complicated words do not necessarily add significant entropy unless used in abundance.
The practicality of typing long passphrases is a concern due to passwords not being visibly echoed on screens.
Lastly, despite the mathematical advantage of the Horse method, passphrases may not be as beneficial as initially thought, as empirical studies show similar usability issues between system-assigned passphrases and random passwords.


Question: does constant charging harm my android cellphone?

Response:
If your phone's charging circuits are sophisticated enough, it should be able to trickle charge without causing battery overcharge or poor conditioning.
Most modern cell phones utilize lithium-ion batteries, which are designed to be charged frequently, and although some chargers may waste energy by getting warm, there's no harm to the battery if it's left charging for a few hours longer than necessary and the battery won't be overcharged.
It is also advised to avoid frequent full discharges, as lithium-ion batteries perform well under several partial discharges with frequent recharges.
All devices should automatically stop charging once full but may resume if the charge drops slightly, and batteries are usually good for about 1000 charge cycles before experiencing significant degradation.
Charging circuits are engineered to be safely connected 24/7, but to minimize battery degradation, the phone should spend minimal time at full charge.


Question: why do people hesitate to use python 3?

Response:
Firstly, the sentiment "If it ain't broke, don't fix it" is a prevailing mindset, particularly when certain libraries, like XYZ library, lack a 3.0 port, and the transition involves complexities due to the elimination of older-style classes in "Python 3.0", so porting old code is not so simple.
Additionally, there was already a huge number of users dependent on Python 2.0, and features back in the Python 2 days seemed a lot more compelling than those provided by "Python 3".
For existing businesses, there is often no compelling reason to invest time, money, and effort in migrating to Python 3, especially when the existing feature set remains unaffected.
The lack of support for Python 3 in major server frameworks and web frameworks further deters adoption.
Also, Python 3 is viewed favorably for new projects if all required libraries are already ported to Py3k; otherwise, Python 2.7 is considered a pragmatic choice, providing compatibility with most existing libraries while allowing gradual adaptation to "Python 3".
The initial Python 3.0 release faced challenges, including critical issues with poor IO performance, making it impractical for many use cases.
Another consideration is that Python 3 doesn't let you play fast and loose with text encodings the way Python 2 does.
Unless engaged in heavy i18n work, there are perceived to be no compelling reasons to switch to "Python 3".
Distribution challenges, where some distributions don't make Python 3 readily available, also contribute to the hesitation.
Furthermore, the shift in integer division behavior in Python 3, which may impact existing code, has been identified as a significant concern.


Question: how to separate mouse and trackpad settings?

Response:
You can install the utility Scroll Reverser for macOS which lets you reverse the scrolling behavior only for the mouse.
You can also use Karabiner to edit the two settings.
Or use a Logitech M185 and the app from Logitech, which has the option to separate trackpad and mouse scroll directions.
With an Anywhere MX 2 mouse, the Logitech Options software solves this problem.
A BetterTouchTool also solves this with a single checkbox.


Question: what does the windows flag in the linux logo of kernel 3.11 mean?

Response: In choosing the name "Linux for Workgroups", Linus Torvalds was making a joke and paying some kind of homage to Windows 3.11.


Question: how can i increase the number of volume levels?

Response:
For enhancing volume control on Android, one could employ various strategies such as flashing a different ROM, using alternative apps with their own volume control, or modifying the phone's operating system if the device is rooted and one is comfortable with the associated risks.
The Fine Volume Control V2 app offers up to 100 volume levels and serves as a temporary fix, while the Xposed module VolumeSteps+, developed by Kuba Kalamarz, allows for the customization of volume steps across different system functions, assuming certain prerequisites like root access are met.
Moreover, adding the line, ro.config.media_vol_steps=30, to the build.prop file which is located in /system, via root access or a custom recovery could easily adjust volume steps.
The Samsung SoundAssistant app provides another solution with adjustable increments for volume control system-wide and per-application settings.
Finally, a simpler method involves enabling "Disable absolute volume" in the Android developer options for improved volume control granularity.


Question: windows azure vs amazon ec2 vs google app engine

Response:
Google App Engine (GAE) is positioned higher within the platform as a service stack compared to AWS and Azure.
It does not offer a static IP and has some limitations that may result in being filtered or blocked.
One of the consequences is the inability to set up site-specific HTTPS certificates.
Nevertheless, it operates differently by dynamically loading and serving pages, helping to maintain low costs.
On the other hand, AWS and Azure provide a static IP and a dedicated VM, which allows for functionalities like HTTPS certification and relational storage support.
They can also handle longer tasks beyond GAE's 30-second CPU processing limit.
Due to these differences, AWS and Azure may be more suitable for customer bases in countries with internet restrictions or for tasks requiring a static IP, DNS setup, relational databases, or longer processing times.


Question: what is the exact difference between a terminal, a shell, a tty and a console?

Response:
A terminal, often a remote piece of hardware, is synonymous with tty, representing a text input/output environment.
It is a session capable of receiving and sending input and output for command-line programs, functioning as an interface with a display for output and a keyboard for input.
Additionally, a terminal is physical hardware with a keyboard and output devices connected to a mainframe.
In essence, it is the space where a computer and a human interface.
On the other hand, the file representing a terminal is traditionally known as a tty file, and tty serves as either a terminal or a kernel subsystem supporting terminals.
TTY, which stands for teletypewriter, is a terminal specifically used for typing text messages.
The shell, defined as a command-line interpreter, is a program responsible for controlling and running other programs.
It serves as an application, such as bash or tcsh, helping users interact with the system.
A console must be a physical piece of hardware connected to or part of the host, typically serving as the primary interface for managing a computer.
Again, the console is a special type of terminal directly connected to the mainframe for OS administration, and it can be where status and errors are reported (e.g., /dev/console).
It encompasses the hardware display and keyboard used for system interaction.


Question: how can i find the hardware model in linux?

Response:
One way is by using the dmidecode | grep -A3 '^System Information' command.
Alternatively, if the manufacturer supports it, dmidecode -t baseboard will provide you with the computer's DMI in a readable format.
You can also try, sudo dmidecode -s baseboard-product-name.
Meanwhile, dmidecode -t 1 would also provide you with the relevant system information.
Away from dmiecodes, sudo lshw -short and lshw -short | grep system also work.
Finally, the system information tool inxi shows the information cleanly, without needing root access as with dmidecode.


Question: are vectors and arrays the same?

Response:
Vectors aren't exactly arrays, but a vector is a 1-dimensional array.
In programming, vectors and arrays are the same thing and are used interchangeably.


Question: where is the folder that termux defaults to?

Response:
The default directory for Termux is given as /data/data/com.termux/files/home.
To confirm the current working directory, the `pwd` command is used.
Furthermore, the `$HOME` variable query can also be utilized to reveal the "default folder" in which Termux operates.
Additionally, interactions with files such as browsing, creating, and manipulating can be performed within the Termux environment in this directory.
It's possible to manipulate the Android directory from Termux as well, but certain permissions must be enabled, specifically storage permissions, which allow for file creation in the local storage of the device.


Question: how do organizations check *what* has been hacked?

Response:
The technique to identify a weak spot in security is to find the hack, the hole, or the weak spot.
Syslog, dmesg, access.log, and error.log are essential to confirm any suspicions of such vulnerabilities.
System forensics is an approach used to examine which system components or assets have been compromised, often through analysis of logs.
For a comprehensive understanding of a security breach, Forensics entails multiple strategies, including Disk Forensics for recovering deleted files, and Memory Forensics for analyzing a captured memory snapshot.
Using tools like Syslog, firewalls' logs, and IDS and router logs can help check various aspects of a system's security status.
Intrusion Detection Systems (IDS) like Snort may record irregular activities and can be a vital tool in Forensics.
Attackers can be detected through system logs, but they can manipulate or erase them if not securely stored.
RDBMS auditing is a significant asset in an investigation related to data access, as it allows for the reconstruction of stolen data sets, as exemplified by SQL Server Audit, which can log audits to the Windows Security log.
The analogy with security logs in a residential burglary illustrates that such logs provide insight into unauthorized access attempts.
To understand the extent of data transferred in and out of a network during an attack, some organizations implement deep packet inspection alongside tools like IDS for real-time alerting.


Question: is there a google calendar mac desktop app?

Response:
Yes, the built-in Calendar app allows you to add Google Calendar accounts directly.
Alternatively, you can use third-party apps like Sunrise, which offers a user-friendly interface and allows you to integrate your Google Account.
Another option is Fluid, a tool that wraps any URL into a native shell, providing a standalone application for Google Calendar.
Additionally, you can add Google Calendar as a Chrome App with a standalone window.


Question: override itunes media keys (play, pause, etc) for spotify?

Response:
NoMitsu has created a one-click installer that patches the remote control daemon, the app responsible for managing the media keys.
The app BeardedSpice is does an excellent job and offers a convenient way to ensure your media keys prioritize Spotify, while also working with numerous other media players.


Question: what is the difference between kali linux and debian?

Response:
Kali is built upon Debian; however, it integrates some packages that aren't in Debian packages, alongside combinations from different Debian repositories.
Consequently, replicating the Kali environment on Debian would require a substantial amount of work, including modifying package repositories, back-porting from other Debian repositories, and sourcing packages from other locations.


Question: has not everyone can be a programmer been studied?

Response:
Yes, a well-known paper that effectively predicts who is destined to be a programmer references a cognitive study by Prof Richard Bornat and Doctor Ray Adams, which speaks to a consistent trend across programming education known as the 'double hump'.
The study suggests two distinct groups: those who can learn to program and those who cannot, each manifesting its own bell curve.
Despite numerous educational strategies attempted over the decades, this double hump phenomenon persists.
Astonishingly, a significant percentage of students, ranging from 30% to 60%, fail their first programming course in university computer science departments.
This has been a constant since the first programming courses began in the 1960s.


Question: why is object oriented programming so hard?

Response:
For individuals new to the concept of object-oriented programming, or accustomed to procedural programming, transitioning to an object-oriented paradigm can be time-consuming and requires a lot of practice.
Newcomers to programming might find OOP challenging because of the unfamiliar concepts involved, and poor teaching or teaching OOP from the beginning without a solid foundation in basic data structures and binding/higher order functions can hinder comprehension.
Additionally, the tools used for OOP may not seamlessly facilitate the learning process.
Furthermore, tasks such as telling a window to open itself may seem unusual in an OOP context.
The disparity between the basic explanation of OOP and its real-world applications further contributes to the perceived difficulty.
Also, OOP is not a paradigm that's actually natural for modeling anything, inheritance in OOP doesn't follow most people's mental models, and because we do not think in terms of properties and methods of real life objects.
Lastly, it can also be a question of motivation: it's harder to learn something when you don't see why, and also when you can't look at what you did and figure whether you did it right or not.


Question: airpods: extremely poor mic quality on mac

Response:
A temporary solution is to switch the mic from the AirPods mic to the internal microphone.
Apple is looking at this issue, and improvements might be forthcoming in future firmware updates.
It is currently recommended to use the Internal Microphone for Recording and the AirPods for playback during calls.
This is due to the AirPods switching to the SCO codec, which affects sound quality when the AirPod mic is activated.
Downloading the "Bluetooth Explorer" tool from @Alex-Ruyven unofficial link and attempting to force the use of the APTx codec works only partially, as the SCO codec is still employed when the microphone is activated.
A created menu bar app can be used to automatically select the built-in microphone as the default input, potentially improving sound quality and battery life.
By removing the AirPods as an input channel in the Audio MIDI setup, one can revert to high-quality stereo output.
Deleting specific configuration files and then resetting the NVRAM is a step Apple support recommends to address the issue.
If using conferencing software like Zoom, changing the mic source within the application itself can sometimes resolve the problem.


Question: how do so (shared object) numbers work?

Response:
Binaries themselves know which version of a shared library they depend on, and request it specifically.

The numbers in the shared libraries are convention used in Linux to identify the API of a library; typically the format is: libFOO.so.MAJOR.MINOR, and there is usually a symbolic link from libFOO.so to libFOO.so.MAJOR.MINOR.

Inside a shared library file is a field called the SONAME, which is set when the library itself is first linked into a shared object (so) by the build process, so SONAME is actually what a linker stores in an executable depending on that shared object is linked with it.

The installer will look up whether or not hello.so.1 is installed on the system by checking ldconfig.


Question: how can i run a cron command with existing environmental variables?

Response:
In the crontab, before you command, add . $HOME/.profile, for example: 0 5 * * * . $HOME/.profile; /path/to/command/to/run.

The general practice is to specifically set all required environmental variables in a script that is to be run from a cron job.

You can use a wrapper script, which is a script launched by cron: in ~/.cronfile you specify the environment for your cron jobs.

A working solution is: 0 5 * * * SOME_ENV_VAR=some_value some_command some_parameters.

Run the script with cron and have the environment in the script, using in the crontab -e file: SHELL=/bin/bash */1 * * * * $HOME/cron_job.sh In cron_job.sh file: #!/bin/bash source $HOME/.bash_profile some_other_cmd.

You can run the script with cron and tell bash to login.

Add BASH_ENV=/home/user/.profile to the crontab.

Setting PATH with the path of commands may help, and it is even better if you can later use a template and detemplatize.

You can put global environment variables in /etc/environment, which will be loaded when a program is run by the crontab, for example: env | grep ORACLE_HOME >> /etc/environment service crontab restart.


Question: ios 12 is how many gb?

Response: The space taken for iOS 12 is 5.1 GB after restoring to factory defaults, or 7 GB on a relatively clean install.


Question: can we delete fsd files?

Response: Yes, although they'll just be recreated as you sync back and forth your OneDrive folder(s).


Question: manually generate password for /etc/shadow

Response:
Method 1: (md5, sha256, sha512) openssl passwd -6 -salt xyz yourpass (note: passing -1 will generate an MD5 password, -5 a SHA256 and -6 SHA512 (recommended)); Method 2: (md5, sha256, sha512) mkpasswd --method=SHA-512 --stdin (the option --method accepts md5, sha-256 and sha-512); Method 3: (des, md5, sha256, sha512).

In Ubuntu 12.04, you can use mkpasswd (from the whois package): Overfeatured front end to crypt(3) mkpasswd -m sha-512 -S saltsalt -s <<< YourPass.

Using Python3: python3 -c 'import crypt, getpass; print(crypt.crypt(getpass.getpass()))' getpass.getpass() will prompt you for a password on the command line.


Question: how can i shutdown my android phone using an adb command?

Response:
To power off your phone, you can execute the adb shell reboot -p command, which will shut down the device.
Alternatively, you can access the Android shell and issue the shutdown command to turn off the phone.


Question: locate vs find: usage, pros and cons of each other

Response:
Locate uses a prebuilt database, which should be regularly updated, while find iterates over a filesystem to locate files; locate has one big advantage over find: speed, but it can be inaccurate if the database has not been updated.

Locate typically lists all files matching your pattern, leaving it to grep filtering and similar to cut this down to size, while find can do things to files it finds, one such operator being -exec.

Find is not intuitive for a novice or occasional user of Unix, and, historically, some versions didn't have the -print option as the default; locate is less flexible, but far more intuitive to use in the common case.


Question: unfortunately has stopped google play?

Response:
One solution is to simply update Google Play Services to the latest version, which you can download from APKMirror.
Alternatively, you can clear the Google Play Services cache and/or the Google Services Framework cache after doing a force stop on the app.
Or, uninstall the updates of "Google Play Services" and restart your phone.
The problem might also originate from your ROM that may need to be replaced with a more stable one.
Of course, don't forget to check your internet connection as that could be the source of the problem.


Question: disable automatic itunes launch when iphone is plugged in via usb

Response:
In iTunes, you can prevent the software from automatically interacting with your iPhone by unchecking options such as "Open iTunes when this iPhone is connected" or "Automatically sync when this iPhone is connected" in the Summary tab, depending on your iTunes version.
Additionally, to reduce automatic processes further, consider disabling iTunes Helper by removing it from your Login Items list through the Users & Groups section in System Preferences.


Question: how much should i be using let vs const in es6?

Response:
The recommended practice in programming is to use constant declaration keywords like const, final, or readonly, whenever it's possible to promote immutability and reduce bugs related to unexpected variable changes.
For variables that won’t be reassigned, such as non-array and non-object data types, const is considered a good choice.
It's essential to make liberal use of const to promote more robust coding, especially in areas where its use makes sense.
However, when dealing with mutable entities like objects or arrays, let might be the better option, given that the properties of these types can still be altered even when defined with const.
For code readability and understanding, it's suggested to limit the use of let to short-lived variables with limited scope and without subsequent changes after their initial assignment, while reserving const for values constant across the module, and var for ambiguously variable names or those that aren't suitable for let.
Finally, use const by default in ES6, and let only when reassignment is necessary, aligning closely with the language specification's intent.


Question: how does imessage know that the recipient is an ios 5 device?

Response:
iMessage identifies iOS 5 devices by associating mobile numbers with device IDs stored on Apple's server for APN.
It utilizes the Device ID to discern whether another device is running iOS 5.
The use of wizards also plays a role in this identification process.


Question: password rules: should i disallow leetspeak dictionary passwords like xkcds tr0ub4dor&3

Response:
Consider using 2-factor authentication because no password complexity scheme will protect you from user actions.

No, you should not disallow "leetspeak" dictionary words per se, but treat them like regular dictionary words, noting that Tr0ub4dor&3 is equivalent to six random printable characters of complexity, and a weak password, so if six random characters is too weak, then you should disallow "leetspeak" dictionary passwords.


Question: how to insert text before the first line of a file?

Response:
To insert text into a file on the previous line, one may use sed's insert (i) option, or use sed '1 i\ your_text' your_file to insert text before the first line.
For updating text at the beginning of files with at least one line, a the sed command "$ sed -i '1s/^/new_text\ /' file_name" can be used, adjusting to accommodate different sed versions and shells.
Other options also exist, such as using the POSIX standard tool "ex" or utilities like GNU awk, the latter allowing the addition of text even to empty files.


Question: gpt or mbr: how do i know?

Response:
There are several ways to find out whether you have a GPT or MBR disk: one simple way on a Linux system is to use "gdisk tool," which may bring up a message stating "Found invalid GPT and valid MBR; converting MBR to GPT format in memory," indicating an MBR-style disk.
Other options include the "parted -l" command, which determines the type of partition table; "check_scheme() { fdisk -l $1 |grep "Disklabel type:" |awk '{ print $3 }' }", a function that can be employed to identify the disk label type; the "sudo fdisk -l" command, which identifies the Disklabel type as 'dos' or not; or "blkid," which can be used to discern between GPT and MBR partition types.


Question: does curl have a timeout?

Response:
The curl command in Linux allows you to control connection timeouts and the maximum time for an operation.
Explicitly, there is the --connect-timeout option to set a time limit for the connection phase and the --max-time option to limit the total time allowed for an operation.
For critical time-sensitive operations, you might use the --max-time option with a parameter like 900 seconds (15 minutes) and the --connect-timeout for about 60 seconds (one minute).
There is also a utility known as timelimit, which can effectively limit the absolute execution time of a process.
This tool allows you to define warnings and kill signals alongside their respective timeouts to manage process execution time.
If you are using MacOS and have coreutils installed, the GNU timeout command, which is part of that package, can be an alternative.
For instance, you could employ 'gtimeout' followed by the duration and the command you wish to run, terminating the command if it exceeds the specified duration.


Question: how can i avoid my macbook pro giving me minor shocks?

Response:
One effective approach, as suggested is to use the adapter with a three-pin extension cord.
This seems to fix the issue of static shocks when the Apple extension cord is not utilized with the power adapter.
Another option is to purchase a cable designed to "ground" the appliance, reducing the sensation of shocks.
Some users have found that dry skin, especially in hot and dry climates, can contribute to the problem.
Alternatively, an unconventional but mentioned solution involves putting on shoes while working with the MacBook.


Question: multi-mode and single-mode fiber differences

Response:
Distance and cost are factors: singlemode fiber often costs less than multimode fiber, but the optics to drive it are twice the cost of multimode fiber optics.

Multimode Fiber (MMF) uses a longer wavelength (850nm) and much wider beam, and generally has a reach up to ~550 meters, whereas Singlemode Fiber (SMF) uses short wavelength (1310nm+) and narrow beam, with the potential to reach 10,000 meters (40,000 meters with ER).

MMF uses a much bigger core, and so the optics are cheaper, but suffers greater modal dispersion where multiple modes of propagation result in a time-smearing of the received signal, hence, distances have to be shorter.

Singlemode fiber (SMF) has much tighter tolerances for optics used, the core is smaller, and the laser wavelength is narrower, meaning that singlemode fiber has a lower power loss characteristic than multimode fiber, and has the capability for higher bandwidth and much longer distances in transmission.


Question: whats the difference between /sbin/nologin and /bin/false

Response:
The primary role of '/bin/false' is to terminate with a non-zero exit code, which is utilized in scenarios where a login attempt should be immediately rejected.
Conversely, '/sbin/nologin' is recognized as a legitimate shell particularly in contrast with '/bin/false', and its purpose extends to instances where a command passed to a program should result in an error and immediate exit.
Additionally, while both '/bin/false' and '/usr/sbin/nologin' can be used to inhibit user logins, the latter is specifically designed for this purpose and notifies the user they cannot log in.
Furthermore, '/bin/false' is part of the GNU Coreutils, and '/sbin/nologin' is provided by the util-linux project, highlighting the different origins and roles they play within Linux systems.


Question: can i use 2 android phones as walkie talkie? (without internet!)

Response:
Mesh Wi-Fi networking on Android smartphones has been successfully enabled, as evidenced by a group that conducted tests.
Additionally, there is an app called Wi-Fi Walkie Talkie that can be utilized for this purpose, known for its simplicity and the fact that it is open-source and ad-free.


Question: does vm have different ip?

Response:
Virtual machines will receive the same IP address from a DHCP service when they share the same Ethernet MAC address.
There are some options to avoid IP conflicts: different virtual machines can have distinct Ethernet hardware addresses, the IP addresses can be explicitly configured through DHCP, or fixed IP addresses can be assigned.


Question: why do so many applications require permission to read the phone state and identity?

Response:
The permission allows apps to read a phone's IMEI, which serves purposes like copy-protection or user tracking.
Android operating systems before version 1.6 did not require apps to request certain permissions explicitly, granting them by default, but from version 1.6 onward, these permissions must be specifically requested by the app.
Advertisers often use permission to access a phone's ID for tracking.
Finally, it's clarified that only apps targeting Android version 1.5 will receive the extra permission by default, without the developer adding it expressly.


Question: how can i mount an smb share from the command line?

Response:
In relation to mounting file systems, a useful command is: "mount -t smbfs" with your password and username (if required), machine name, share name and destination folder.
For automatic mounting at system boot, alterations to "/etc/auto_master" and the creation of "/etc/auto_smb" with appropriate mount points and options are recommended.
The utility of "Using AppleScript" is a good option for its integration with Keychain through the execution of a custom Bash function.


Question: unix/linux undelete/recover deleted files

Response:
To recover deleted files, one could utilize the "Linux debugfs Hack: Undelete Files" which provides a straightforward guide on file recovery using debugfs commands.
One user declares ext3grep superior to debugfs, photorec, and extundelete programs, finding its syntax very easy.
Using 'del' instead of 'rm' is also suggested as it has an undelete function and is compatible with any file system.
Other methods include 'grep -a -C 200 -F 'Unique string in text file' /dev/sdXN' where /dev/sdXN is the partition containing the lost file, using the testdisk utility ('Undelete' within the '[Advanced] Filesystem Utils', 'ufs-explorer and photorec', or 'ext4magic'.
When using 'ext4magic', it is advised to clone the HDD before attempting recovery and to avoid saving to the HDD you are trying to recover.


Question: how to remove duplicate lines inside a text file?

Response:
In Perl, you can eliminate duplicate lines from a file while preserving their order with the command `$ perl -ne 'print unless $dup{$_}++;' input_file > output_file`.
Alternatively, an awk one-liner `awk '!seen++' filename` can achieve a similar result.
Using standard utilities involves a sequence of commands numbering lines, sorting and uniquifying by ignoring line numbers, and then sorting by line numbers before cutting off these numbers to output the deduplicated content.
Python also offers a one-liner solution to sort and remove duplicates from a file: `python -c "import sys; lines = sys.stdin.readlines(); print ''.join(sorted(set(lines)))" < InputFile`.
The Unix `sort` utility can be used with the `-u` flag to directly sort and remove duplicates from a file, for example, `sort -u big-csv-file.csv > duplicates-removed.csv`.
For in-place file editing without creating a new output file, GNU awk provides an option with `gawk -i inplace '!a++' file`.
`uniq` command is used to report or filter out repeated lines in a file, usually post sorting since it works on adjacent duplicates.
If preserving the original line sequence is not a concern, a combination of `sort` and `uniq` can be used as in the command `sort duplicates.txt | uniq > noDuplicates.txt` to remove repeated lines.


Question: are ssh usernames case sensitive?

Response:
In multiple types of systems and local accounts, usernames are found to be case sensitive, although some state that this is variable when using LDAP.
In Unix systems, not only are usernames case sensitive, but the convention is also to avoid using uppercase characters to prevent potential issues.


Question: why not allow spaces in a password?

Response:
For security concerns, it discourages people from using actual sentences as passwords which could be insecure if they had real meaning.
Moreover, there is nothing insecure about a space in a password if it maintains good entropy.
Banning space characters in passwords is generally a bad password policy.
Passwords with leading and trailing spaces may cause issues for individuals who frequently copy and paste without care.
The issue with spaces in passwords relates to programmatic semantics.
Spaces and certain special characters may be processed differently across various computing platforms.
From a convenience standpoint, not having spaces in passwords is a very good policy, especially as seen from the perspective of customer support.
The Space key on a keyboard often makes a distinctive sound that can aid someone in guessing the structure of a password when heard.


Question: are dell docking stations compatible with mac?

Response:
Dell does not support mac OS for this product, and they do not guarantee that it will work with your MacBook Pro, noting that your MacBook Pro does not support MST (multi-stream transport) via the USB-C cable you plug in, which is required for this dock's "extended mode" to work even with just two monitors.

In addition, this product is not fully compatible with a MacBook as it doesn't communicate powerinfo with the Macbook, so doesn't supply it with enough power.


Question: can vlans span across routers?

Response: Yes, you can, and it's recommended to do so.


Question: whats the purpose of the randomart image for user (not host) ssh keys?

Response:
The primary function of SSH keygen randomart is to ease the process of validation.
Additionally, randomart is a lot easier for humans to differentiate between than long strings of hex code.


Question: how to copy a file from a remote server to a local machine?

Response:
To transfer files using SCP, the command syntax to consider is `scp username@source:/location/to/file username@destination:/where/to/put`.
Additional insights on SCP usage can be obtained by referencing `man scp`.
An alternative for file synchronization and transfer is `rsync`, which provides commands like `rsync -avzh --stats --progress remoteuser@remoteip:/path/ localpath`.
For local network transfers where security is not a concern, `netcat (nc)` is recommended as it is deemed the fastest method within a trusted network.
When copying a directory and its contents via SCP in Linux, the command follows the structure `scp -r root@<remote IP>:~/folderinremoteuserdir ~/folderinlocaluserdir`.


Question: how did tech-supportcenter phishers trick google?

Response:
The scammers likely gained control over third-party advertiser systems, exploiting their redirect chains to misdirect users to fraudulent sites.
Advertisers seeking to track clicks and validate ad billing often employ ClickURLs, which proceed to the legitimate destination despite displaying a different, more presentable DisplayURL, a practice susceptible to phishing exploitation.
Access to a brand name in an AdWords account comes from a whitelisted ad agency because it's difficult to gain this access without the help of a trusted agency.


Question: osx yosemite - mission control stopped working

Response:
A simple reboot of the system restores its functionality.
Alternatively, restarting the "Dock" process without a full reboot using the 'killall Dock' command in the Terminal proves effective for regaining control.
For a more direct approach, execute the command 'defaults write com.apple.dock mcx-expose-disabled -bool FALSE' in the Terminal to enable the feature, followed by the 'killall Dock' command to restart the Dock.
Lastly, adjusting settings directly in the OS—such as setting the "Dashboard:" dropdown to "As Overlay" in the System Preferences under Mission Control—solves the issue.


Question: what does etc stand for?

Response:
According to various opinions offered, the term "et cetera" is used to indicate additional unspecified items in a list or directory, as in all the rest that are not further categorized.
Historically, the term "et cetera" comes from Latin and means "and the rest," but it has also been interpreted in the technology world as "editable text configurations".


Question: does having a longer ethernet cable slow your connection?

Response:
In theory, yes, to a very tiny extent, as the electric signal will be slowed down by a minimal amount (after all, it travels at 2/3 light speed), but the effect is about one nanosecond per foot of cable, which is unlikely to be noticeable in most cases, especially as a single ethernet cable is limited to 100m.

For all practical purposes, no, there will be no effect on the speed of your connection.

However, a more critical factor is if you were using a gigabit connection, a longer cable could give enough signal deterioration for this to be no longer possible, forcing you to use a slower speed.


Question: file cant be moved by root on os x

Response:
If you encounter security restrictions on OS X 10.11 or newer while trying to modify certain files, you can disable this security feature by booting into recovery mode and using a Terminal command: csrutil disable.
Another method to modify restricted files is to start the terminal in Recovery Mode and delete the file.
For directories that have been locked due to the system's user-level flags, you can execute the command chflags -f -R nouchg directory on a higher-level directory to prevent the problem.
It's also advisable to check if the folder containing the file you wish to modify is locked; to do this, use the 'get info' function in Finder and ensure the locked checkbox is not marked.
In cases where you are unable to delete a file through the terminal, you may have success by using Finder to delete the entire directory that contains the problematic file.


Question: does thunderbolt 2 provide power?

Response: Yes, it can carry power for devices if that Thunderbolt port is part of a device that is connected to an AC power outlet or is operating on battery power.


Question: simple way to create a tunnel from one local port to another?

Response:
Using "ssh" is a common method for port forwarding, which allows connecting a local port on your computer to a remote server's port and will stay open until it dies or it shut down.
OpenBSD netcat arrives pre-installed on Linux and OS X, and another option for OS X bash is to use a bidirectional pipe.
In Ubuntu, the netcat-traditional package provides the traditional "nc" utility, which can be used for similar networking tasks, although it lacks encryption.


Question: powerd process uses a lot of cpu

Response:
Terminating the powerd process via Activity Monitor effectively solves CPU usage issues.
Another proposed solution is a command-line approach, which uses `sudo kill -HUP $(pgrep powerd)` to address the problem without explaining its necessity.
Resetting the System Management Controller (SMC) is recommended as a potential fix for power-related issues on Mac computers.
Although resetting the SMC on a Mac is a known troubleshooting step, as mentioned on Apple's official webpage, it may not address the specific powerd issue some users experience.
For one user, quitting Activity Monitor was the key to resolving the excessive CPU usage by the powerd process.
However, another user observed that powerd only consumes significant CPU resources when Activity Monitor is running, suggesting a link between the two.


Question: how critical is it to keep your password length secret?

Response:
Telling someone the length of your password isn't the worst thing you can do, as you're in essence giving someone a hint about how hard it might be to guess—if your password is very long (17 characters in your example) it's largely useless information—and some recommend against it, while others suggest you actually enhance security by deliberately leaking that information.

However, revealing the length of the password would influence an attacker’s strategy: if your password is weak (short password), an attacker may focus on cracking it, while if the password is strong (long password), an attacker might explore other vectors of attack.


Question: can i share my imacs internet to iphone or ipad over usb?

Response:
Before the launch of iOS 10, the capability to adjust certain device features was possible only with a jailbroken device.
However, this changed with macOS 10.12 and iOS 10, which support the feature without needing a jailbreak or additional apps.
Enhancements to this functionality were included in the later macOS 10.13 as a component of asset caching and were integrated into Apple Configurator 2 to assist with the network setup of multiple iOS devices sharing a Mac network.
The Bluetooth PAN sharing feature was available to all iDevices at one time but currently seems to have inconsistent functionality, primarily working with iPads while most iPhones report failures.
Using Apple's development tool, one can achieve iPhone-Mac-Internet tethering, as detailed in steps between the "Remote Virtual Interfaces" and "Using tcpdump" sections.
Sharing an iMac's Ethernet connection to an iPad or iPhone is also possible with additional hardware requirements, and Bluetooth tethering remains an option mainly for iPads and Android devices.
MacOS Sierra allows Internet connection sharing from a Mac to an iPhone via USB following specific instructions to utilize the iPhone USB option.
Moreover, sharing a Mac's Wi-Fi connection with an iPhone can be achieved by connecting with a USB-Lightning cable and disabling Wi-Fi on the iPhone.


Question: how can i communicate with a unix domain socket via the shell on debian squeeze?

Response:
On Debian, you can make use of a tool named socat for your networking needs.
This tool, also known as a bidirectional data relay, allowing for connections to Unix domain sockets which can be achieved with specific socat commands.
Alternatively, netcat-openbsd, supports a -U option for connecting to Unix-domain sockets.


Question: my right click is not working in kali?

Response:
Kali Linux has an option to turn on/off "Tap to click" in /Settings/Mouse & Touchpad.
This option is unchecked by default, and all you need to do is check it.


Question: how to clear the cache or do a hard refresh in safari?

Response:
To do a full refresh, you can press ⇧ Shift and click the Refresh button, or use the keyboard shortcut ⌘ Command+R.
Clearing the cache is possible with ⌘ Command+E, followed by a refresh.
Alternatively, you can go to Safari > Empty Cache or use the shortcut ⌘ Command+⌥ Option+E.
Another option is to use the combination ⌘ Command⌥ OptionR, which serves as Safari's equivalent to ⌘ Command⇧ ShiftR in Chrome, ensuring a "Hard Refresh" without clearing the cache.
Depending on your Safari version, you might find that Opt+Cmd+E or ⌥ Option ⌘ Command E.


Question: what if kill -9 does not work?

Response:
Kill -9 (SIGKILL) always works, provided you have the permission to kill the process, with the exception of zombie processes, which are harmless as they only consume an entry in the process table.
It will go away when the parent process dies or reacts to the death of its child.
Some users say that the following conditions would prevent a kill: a rootkit, immunity from the kill (the initialization process, kernels  or anything with a PPID equaling 0, a process in uninterruptible sleep, or where a process has restarted automatically.
You can see if the process is a zombie by using top or the following command: `ps aux | awk '$8=="Z" {print $2}'`.
However, if the parent did not read the exit status, the kernel is out of whack, or a remote mount has caused a zombie process that does not stop with unmounting the device or samba, the only method to kill the zombie is the reboot or wait.
You can also try attaching to the process with gdb: `gdb -p <PID> > kill Kill the program being debugged? (y or n) y > quit`


Question: how do i use openssl s_client to test for (absence of) sslv3 support?

Response:
If you need to ensure that openssl s_client uses only TLS, you can force it by using the command "openssl s_client -connect example.com:443 -tls1".
However, it's significant to mention that the -ssl3 option in OpenSSL needs to be enabled during the compilation process, and it might not be available if you are using pre-compiled binaries.


Question: how can i update to a newer version of git using apt-get?

Response:
Performing a search for "git ppa" provides Git stable releases.
You can also install the package by downloading directly from the web page, and installing with dpkg -i.


Question: is it acceptable that a skilled professional pentester deletes or modifies sensitive data in production unintentionally during a pentest?

Response:
There's no way that a pentester can 100% assure that data will not be modified or deleted, in the same way as they can't assure that system availability won't be affected, and there are no absolute guarantees something will not accidentally be deleted when you are trying to break things.

Yes, it is acceptable for data to be modified and this should be on page 1 of the contract, as the client company needs to prepare for things to go wrong, making backups and recovery plans; if the site is really, really critical, create a complete clone on a different server, then test that clone first.


Question: is it possible to rotate images in preview in degrees other than 90?

Response:
While it seems there is no obvious way to rotate images in degrees other than 90, there is in fact a 'hidden' feature that allows you to do so.
Simply hold the Option button down and use two fingers on the trackpad to rotate the image.


Question: how do quick & dirty programmers know they got it right?

Response:
To confirm that software has been correctly developed, thorough testing by a good quality assurance (QA) team is critical, ensuring that it passes all tests set out to assess its functionality.
Programmers who adopt a "quick and dirty" approach often don't clean up their work later, leaving a legacy of code that may fail in unforeseen ways, placing both the company and its clients at risk.
Moreover, many programmers believe their quick solutions are correct without truly knowing since distinguishing the accuracy of their work without testing can be challenging.
Testing is key in establishing whether the code written under rapid and potentially sloppy conditions is indeed reliable.


Question: what is the difference between libreoffice and libreoffice vanilla?

Response:
LibreOffice Vanilla and LibreOffice Fresh are nearly identical, with the key distinction being that the Fresh version prompts for a donation during download.
Moreover, LibreOffice Vanilla for Mac lacks certain Java-based features, which leads to the omission of the HSQLDB engine in Base, as well as some reporting features, and Java-based extensions are also unsupported.
Additionally, at the time this was documented, LibreOffice Base did not have full support for M1 Silicon Macs, whereas Vanilla did support these newer Mac models.


Question: what is the difference between an api and an sdk?

Response:
"SDK" is collective in a larger sense than API, as All SDKs are APIs but not all APIs are SDKs.
In other words, an SDK appears to be a complete set of APIs.


Question: download using wget to a different directory than current directory

Response: If you know the name of the file ahead of time, you can use the -O option with wget to tell it where to write the file: wget -P /var/cache/foobar/ [...] wget --directory-prefix=/var/cache/foobar/ [...].


Question: has it been mathematically proven that antivirus cant detect all viruses?

Response:
Determining if a program is malicious is undecidable in the general case, as per Rice's theorem.
Fred Cohen demonstrated in 1987 that it's not possible to create an algorithm that can detect all possible viruses.
It was mathematically proven by Alonzo Church in 1935-36 and Alan Turing in 1936 that certain problems are undecidable.
It cannot be mathematically proven that all viruses can be detected since the proposition can't be mathematically formulated in the first place.
If false positives are not permissible, it's not feasible to detect all viruses; there will always be a contradiction.
Bruce Schneier stated that it is mathematically proven that there is no "cure" for viruses since it is always possible to create one that cannot be stopped by any existing antivirus program.


Question: what is the difference between error and fault?

Response: A fault is the adjudged or hypothesized cause of an error.


Question: ssh-add is not persistent between reboots

Response:
To manage SSH identities on a Mac, particularly in Sierra, one efficient method is to use the "UseKeychain" option, although its security has not been thoroughly vetted.
For MacOS Catalina version 10.15.2, it's advised to ensure your SSH key has a passphrase, which the keychain requires.


Question: how can i monitor disk io?

Response:
For disk I/O monitoring, several tools are mentioned across the passages, such as iotop, which displays disk read and write operations in real-time.
The sar command from sysstat can provide output that includes time spent waiting on I/O—the %iowait.
Dstat is another tool preferred for its ability to show statistics per disk and is noted for using colors to provide a clear overview.
Direct querying of system files like /sys/block/sda/stat or /proc/diskstats can be used for a quick status check on disk I/O without additional tools.
Centreon, a tool built on Nagios, is recommended for long-term performance monitoring with graphing capabilities for resource performances.
For more comprehensive monitoring and understanding, one might prefer tools such as iostat, Iozone, SAR, and vmstat.
The sudo iotop command with specific flags such as -aoP is recommended for viewing accumulated output and process-specific I/O data.
Nmon, which works for both disk and network with processes, is also available and has a history of use on AIX before being ported to Linux.
Lastly, diskgraph is a command-line tool that plots disk I/O in a terminal, providing visual bandwidth and in-flight I/O operations in different colors.


Question: why is it dangerous to open a suspicious email?

Response:
Opening a suspicious e-mail is riskier because more stuff is processed when you actually open it, and it is possible your mail client has an unknown bug– or a known but unpatched one–that could allow an attack.

Even if nothing actively bad happens, many passively bad things can happen, as just by opening an email in Gmail, or other email clients that do not block images, you may be sending data to potential attackers, for example you might view a one pixel transparent image tagged with your email address that flags you as the kind of person who opens and reads suspicious email, putting you on a list for subsequent email-spam bombardment, that could cause you to be scammed.


Question: is visiting https websites on a public hotspot secure?

Response:
In practical terms, encryption initiated by root SSL authorities is suitable for insecure lines, and generally, TLS does not have issues with man-in-the-middle attacks.
HTTPS is considered secure even on public hotspots due to the nature of its key exchange and encryption mechanism, ensuring that the master secret and pseudo-random numbers are transmitted securely.
HTTPS demonstrates a strong resistance to decryption from packet sniffing, but the server authentication reliability may be compromised due to certain weaknesses in the distribution of CA certificates.
A session carried out entirely over HTTPS is quite safe, with browser requests and server pages being encrypted; however, many sites after the initial authentication revert to HTTP, leaving session IDs vulnerable.
Utilizing a VPN can provide an additional layer of security when accessing the internet via an unencrypted wireless connection.
SSL/TLS is not inherently more vulnerable on public Wi-Fi than it is on a "regular" internet connection and is designed to function in open channels.
Ultimately, SSL/TLS is secure, partly due to the key exchange protocol which stops malicious users from decrypting traffic or sending messages in another user's name.


Question: do macbooks have a true hibernate option?

Response:
Yes, MacBooks do have a true Hibernate option, and Apple refers to it as Safe Sleep.
Additionally, there is a free app called Hibernate by Patrick Stein that users have employed to enable hibernation on their Macs.
This feature is available on newer machines, with its debut in the 2011 MacBook Air, and is known as PowerNap.


Question: how to transfer whatsapp voice message to computer?

Response:
To transfer voice notes from WhatsApp on your device to your computer, you have the option to select the "Share" feature within the app and send the files via Email, Gmail, Bluetooth, or other available services.
You can also move the files onto your phone's SD card, connect your phone to your computer via a USB cable, then find and transfer the files via File Explorer on your PC.
Alternatively, you can choose to attach all the desired voice notes to an email and, from your phone, send them to your own email address.
Upon receiving the email on your computer, you can then download the voice note attachments.


Question: grokking java culture - why are things so heavy? what does it optimize for?

Response:
Enterprise solutions demand heavy tools contributing to the preference for heaviness in the Java ecosystem.
Java's conservatism in adding features, aimed at preserving backward compatibility and ensuring long-term sustainability, results in a language that lacks a lot of modern syntax to express concepts tersely.
The optimization focus of Java aligns with the development of high-value software intended for extensive maintenance by large teams over many years.
As a traditionally single-paradigm class-based object-oriented language, Java emphasizes explicitness and consistency in its design, optimizing for these qualities.
The culture surrounding Java is tailored to create an impression of understanding software development, particularly appealing to managerial perspectives.
Compile-time programmer error detection is optimized, ensuring that no assumptions are made.
Java classes, in this context, are designed not for lightweight data passing but for more comprehensive functionalities.
Additionally, the limitation of returning a single value from a method is a characteristic that further shapes the overall optimization strategy of Java.


Question: which is the safest way to get root privileges: sudo, su or login?

Response:
The safest approach is ssh login using (at least) 2048 long key (with password login disabled) using a physical device to store the key.

Between su and sudo, when you consider a single user, su is a little more secure as an attacker who has found your password can't gain root privileges immediately; while sudo has advantages even over a console login when there are multiple users.

If you are concerned that a compromised user account can be used to sniff the password used for sudo or su, then use a one-time passcode for sudo and su.


Question: any reason not to run linux in a vm all the time?

Response:
When running Ubuntu in a VirtualBox VM, the pass-through of OpenGL acceleration to the host system is unstable and problematic.
Within a virtual machine, if the host computer relies on a wireless network connection, the performance of a VPN on the guest system tends to be highly unreliable.
Initiating VirtualBox also results in a significant surge in power consumption, with the VBoxHeadless process often being the most power-intensive on the user's system.
If a user opts to run Linux as the host system, they might encounter difficulties related to driver compatibility, and achieving proper 3D acceleration might pose challenges.


Question: how to open a new tab in iterm in the same folder as the one that is open?

Response:
To open a new tab in iTerm in the same folder as the one that is open, you can choose "Reuse previous session's directory" in the profile preferences.
Another option is to click on "Advanced Configuration," and then "Edit" to set the working directory separately.
Alternatively, if your preference is to start in the home directory and then navigate to the current directory as needed, you can achieve this by using the open . -a iterm command.


Question: macbook pro: how to disable discrete gpu permanently from efi?

Response:
Apple does not approve of users tampering with the EFI boot system, and any modification could result in severe consequences, including the bricking of your device.
When changing the EFI, you also accept a heightened security risk.
There are several methods to use the integrated Intel graphics on a MacBook Pro under different operating systems, such as using rEFInd or a patched version of GRUB; however, each approach carries its own set of risks, including hard drive corruption or leaving the computer in an unbootable state.
Another approach is to edit the NVRAM variable from Single-User mode, which may circumvent steps that can become problematic with certain macOS updates and can involve using Linux to alter EFI variables.
It's possible to disable the discrete GPU on newer MacBook Pros, but this will remove the ability to directly output to an external monitor using built-in Thunderbolt or DisplayPort outputs.
There are alternatives, such as USB solutions or external GPUs, if you still need multiple displays.


Question: how to find out the dynamic libraries executables loads when run?

Response:
In order to examine the shared library dependencies of a program or shared library, you can utilize the ldd command.
Alternatively, to explore the memory map of a process, the pmap utility provides detailed information and can be executed with additional options for more specific outputs.


Question: whats the rationale behind ctrl-alt-del for login

Response:
The Windows (NT) kernel ensures the Ctrl-Alt-Del key combination is directed exclusively to Winlogon, making it impossible for third-party applications to mimic and capture login credentials.
This Ctrl-Alt-Del combination is considered a Secure Attention Key in Windows, reinforcing that a user is interacting with the authentic login screen and not a fraudulent one.
It is also a defense mechanism against malicious software that tries to intercept passwords by presenting a fake login screen due to its non-interception policy.
Winlogon is the only trusted process that can interpret the Ctrl+Alt+Del sequence, serving as a secure attention sequence to prevent malicious programs from capturing your login information.
The decision to use these particular keys is based on their difficulty to be pressed inadvertently, thus reducing the likelihood of error.
In contrast to Windows, the Secure Attention Key function in Linux uses different key combinations and it reboots the machine.


Question: what to do if caught in a physical pentest?

Response:
When engaging in a Red Team Engagement, if you are caught by security, ensure you follow the police's orders.
They will verify your Permission to Attack and contact the individual responsible for authorizing your activity.
Claiming to be a "security researcher" or attempting to flee the scene are inadvisable strategies, as these could lead to further complications and misunderstandings with security personnel.


Question: is applecare for iphone transferable?

Response:
Yes, according to AppleCare's Frequently Asked Questions, both the AppleCare Protection Plan and AppleCare+ are transferable.
Furthermore, when an individual obtains an Apple product with AppleCare, the previous owner is obliged to transfer the ownership of the AppleCare Protection Plan or AppleCare+ to the new owner if they choose to sell or give the product away.
The option to transfer ownership is provided because the original owner has the ability to cancel the AppleCare protection at any time and may receive a prorated refund.


Question: how can i restart the ssh daemon on ubuntu?

Response:
You can restart the SSH service in Ubuntu using the "service ssh restart" command.
To ensure you have the proper permissions to restart it, use the commands "sudo stop ssh" followed by "sudo start ssh," which makes use of upstart.


Question: what does ampersand mean at the end of a shell script line?

Response: This is known as job control under Unix, where & will cause the shell process to run in the background, and as the sys-snap.sh command continues to run, you can continue to use the shell, without having to wait until the script is finished; without & it will stay in the foreground until the script ends.


Question: macbook unplugged from external monitor thinks its still the secondary desktop

Response:
If your MacBook, after being unplugged from an external monitor, still thinks it's the secondary Desktop, you can use the keyboard shortcut Command + Brightness Up, which serves as the Detect Displays shortcut in Lion.
Alternatively, you can navigate to Displays in System Preferences, hold down the ⌥ Option key, and the Gather Windows button will transform into Detect Displays.
In cases with Mavericks, changing the Rotation setting can prompt the OS to recognize the absence of the external monitor.
Additionally, putting your MacBook to sleep and waking it up immediately can effectively resolve the problem.


Question: how do you exit full screen mode in yosemite?

Response:
To exit full-screen mode in Yosemite, click the minimize/maximize button a second time or press Control-Command-F simultaneously.
Another approach is to move the mouse cursor to the upper-left corner of the screen and wait a second; the 'traffic light' buttons will reappear, allowing you to leave the full screen.


Question: how to remove an environment variable on osx using bash

Response:
Unset it using "unset DYLD_LIBRARY_PATH".
According to the bash reference manual, the only way to unset a variable that has been set is with the 'unset' built-in command.


Question: macos sierra doesn’t seem to remember ssh keys between reboots

Response:
One method to tackle SSH key issues on startup is to implement the ssh-add -A command every time your system boots.
To do this, just add .plist file with the following content to the path ~/Library/LaunchAgents/ or create one with Lingon app: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>ssh-add-a</string> <key>ProgramArguments</key> <array> <string>ssh-add</string> <string>-A</string> </array> <key>RunAtLoad</key> <true/> </dict> </plist> <!-- @@@@LingonWhatStart:ssh-add -A@@@@LingonWhatEnd -->.
Another way is to prevent SSH key hassles is to amend the ~/.ssh/config file to include the UseKeyChain option for all hosts.
However, to ensure keys are retained in the ssh-agent even after a system reboot, simply amending the UseKeyChain will not suffice.
Since MacOS 10.12.2, you should add the following lines to your ~/.ssh/config file: Host * UseKeychain yes AddKeysToAgent yes, then reboot your machine.


Question: how do i get f11 and f12 to behave like normal function keys?

Response:
To get F11 and F12 to behave like normal function keys, you can adjust settings in Preferences under Mission Control.
In this section, two options are configured to use the F11 and F12 keys; to make them behave like normal function keys, set these options to '-'.


Question: which ipods are no longer supported?

Response:
The iPod Classic is not supported by the current software, and Apple Support indicated that there is no backward compatibility available; they advise purchasing a new iPod model.
For users with older iPod models, it's noted that they can no longer sync with the latest iTunes version, but an older version of iTunes installed on a Windows PC could resolve the issue.
However, for managing an iPod Classic, the use of a third-party music manager, like transpod, is recommended as an alternative to the current iTunes software, especially for users who do not have an older iTunes version.


Question: when do you use float and when do you use double

Response:
For most general purposes, the double type should be your go-to option when working with floating-point numbers.
Specialists in fields requiring extensive float-point number crunching where performance and storage are a concern might consider using float only after careful analysis shows that limited range and precision won't hamper the results.
Meanwhile, long double is suitable for use by specialists for circumstances that demand more range or accuracy than double can provide, contingent on whether the platform supports these enhancements.
For general calculations and temporary variables, double is the recommended data type.
The float type may be appropriate when managing large arrays of floating points and can be used if the precision fits the need and the number of floats is extremely high.
However, in modern computer systems, there are few reasons to prefer float over double, except for specific cases like conserving memory or dealing with hardware that offers limited support for double-precision floating-point operations.
Using float or int becomes necessary due to hardware constraints when working with particular platforms that do not support double, like the ARM Cortex-M series.


Question: what features of mavericks are beneficial to you?

Response: Some examples of beneficial features of OS X Mavericks are: move Dashboard in Mission Control; Secret Wallpapers; using the Show Desktop gesture, the motion of the windows now follows the motion of your fingers on the trackpad; preview PSD files (Photoshop Documents) directly in Safari; battery life; improved Multiple Screen support; disable App Nap on a per app basis;  Apple TV makes it easy to see on your TV the media content that is on your Mac with AirPlay; driving directions for iOS; the energy consumption view that collects 8 hours of history; the battery menu in the top bar now shows apps using high amounts of energy; move Dock between monitors; new Safari setting to power off plugins when inactive to save battery life; Control ⌃ + Command ⌘ + Space opens a characters panel including Emojis; bring your home folder's library back with one checkbox; responsive scrolling in Mountain Lion; Mac App Store Notifications now include multiple "Later" options; iCloud Sync Automator and AppleScript Editor; enhanced Dictation; ColorSync utility; iCloud Keychain stores and syncs Secure Notes across Macs; disable Notification Center on the Lock Screen; Gatekeeper; iMessages can be created quickly in Notification Center; see all apps are using your location; full screen finder; Messages now has a color setting called auto, using Speakable Items and Automator to command your Mac by voice; Zoom pictures in QuickLook; Finder messages are now Notification Center alerts; Safari tells you when a tab crashed; LinkedIn and a few others are now supported in Internet Accounts; Mail.app supports exporting emails now as PDF files; automatically installs updates; charging state of an iPad is notified to the user; Finder Tabs Safari Style (Command + T opens a new tab); Activity Monitor tells you what pages a Safari process has open; Side dock has new UI; and Event reminders based on travel time.


Question: delete the last character of a string using string manipulation in shell script

Response:
One user advises that this can easily be done using this regular expression: `n=2 echo "lkj" | sed "s/\(.*\).\{$n\}/\1/"`.
To trim a single character by parameter expansion and for something that is the most portable and shortest answer: `${t%?} `which works in bash, sh, ash, dash, busybox/ash, zsh, ksh, by using old-school shell parameter expansion.
With bash 4.2 and above: `${var::-1}`.
You can also use head to print out all but the last character (`$ s='i am a string' $ news=$(echo -n $s | head -c -1) $ echo $news i am a strin`), but some versions of head, in particular with OSX, do not include the leading - option.


Question: how to record both screen and sound with quicktime on el capitan?

Response:
To record audio when using QuickTime on El Capitan, you'll need to install Soundflower, a virtual soundcard that allows for the capture of computer sound.
Also, alternatives such as ShowMore and Jing can be used as screen recorder, which will get the job done.
If willing to invest in a paid solution, Capto, previously known as Voila, offers helpful features for recording.


Question: adb constantly disconnects, shows device offline

Response:
For issues with Android Debug Bridge (ADB) connectivity, reflashing or updating the ROM on your device can be an effective solution, particularly if you've experienced stability improvements after changing ROMs in the past.
You can test it on another phone to verify if the problem is specific to your device, as there is a possibility it might just be due to occasional instability in ADB.
It is possible to solve the problem in the Windows USB settings by unchecking the option of "Allow the computer to turn off this device to save power".
It's recommended to ensure that unrelated software, specifically Samsung Kies, is not running in the background, as it may interfere with USB connections.
Trying different USB cables and ports or using rear USB ports instead of front ones can also resolve connectivity problems.
Some users have found that switching from USB 3.0 ports to USB 2.0 ports has solved their issues.
Another solution is to directly connect the device to a physical USB port on the machine or through a powered USB hub to ensure the device receives adequate power.
For Windows users, adjusting USB settings by preventing the computer from turning off devices to save power is another way to fix disconnect-reconnect problems.
Adjusting the device's USB configuration settings to MTP by going to Developer options > Networking section > Select USB Configuration > MTP can also resolve driver installation freezes.
Lastly, simply restarting the device and freeing up internal storage space may alleviate some connectivity issues.


Question: what is the difference between halt and shutdown commands?

Response:
In most modern Linux systems, such as Centos, using the halt command will initiate a shutdown unless you are at runlevel 0 or 6.
However, in Solaris 10, the halt command is more brutal as it simply flushes the disk caches and turns off the system without running any scripts or shutting down system facilities.
For AWS EC2 users, executing a shutdown will stop an instance, whereas using halt will terminate it.


Question: do the parent directorys permissions matter when accessing a subdirectory?

Response:
To traverse a directory, it is essential to have execute permission on that directory.
The way a file is accessed, whether through a relative or absolute path, can affect the permissions needed.
Additionally, execute permission on a directory is required to access files within it, even when using a symbolic link.


Question: how to explain heartbleed without technical terms?

Response:
The fatal flaw, known as Heartbleed, exists in the OpenSSL library, which failed to verify that the Heartbeat payload size matched the actual length of the payload.
An example of data leakage from a vulnerable server demonstrates a serious issue whereby memory contents could be exposed to attackers.
Attackers can exploit this by claiming to send a data packet of size "x" while actually sending a much smaller packet, resulting in the server sending back additional data outside of the intended payload, often containing sensitive information.
For example, a bank system update allowed users to send a request to reset multiple debit cards; however, when a user sent a request for only one card, the system returned existing codes for 65,534 other cards belonging to random users.
If an attacker sends a manipulated message with a falsely claimed size like "HEARTBEAT, 1000 letters, CHEESE", OpenSSL would erroneously transmit back more data than it should, potentially including confidential information.
The Heartbleed bug allows for random access to protected information, similar to flipping through the pages of a personal diary without the owner's knowledge.
Depending on how the "What did I just tell you?" is used in communication between computers, a web server with the bug can unintentionally reveal much more information than intended, risking the exposure of user passwords and sensitive data.


Question: is there a way to dynamically refresh the less command?

Response:
Within the Unix 'less' program, using 'F' or 'Shift+F' initiates a 'follow' function akin to the 'tail -f' command, allowing updates to display as they occur.
If you prefer to use 'tail -f' directly, you can pipe your command to it, though this will restrict you from scrolling through your output.
Alternatively, typing 'G' approaches similar functionality but on a one-time basis, which may be advantageous in particular network environments.
If you're accessing 'less' via a command line, you can also use 'less +F' followed by the filename to activate the "follow" feature directly.
For cases where the file content is being modified, 'R' repaints the screen while dismissing any input still in the buffer.
However, should you need to forcefully reload a file, you can open the Help page with 'hq' and then exit, which prompts a file to reload.


Question: do ibooks backup to icloud?

Response: PDF files and non-iTunes store eBook content are backed up to iCloud.