Question: how to compare two dates in a shell?

Response:
For chronologically comparing dates in the year-month-day format, using a standard string comparison suffices.
It's also possible to convert the dates into Unix timestamps for comparison, as timestamps can be easily compared once converted.


Question: how to install dig on centos?

Response:
To install the DIG tool on CentOS, you need to install the BIND Utilities.
To do this using the dnf package manager, type the following command: $ dnf install bind-utils.
On legacy systems, if dnf is not available, you can use yum instead with the command: $ yum install bind-utils.


Question: is there a charge for airdrop?

Response: Airdrop it is always a direct connection (usually wifi or a mix of wifi + bluetooth) between the 2 devices, so your internet quota won't be used at all.


Question: how do i start texteditor from the command line?

Response:
If your default text editor is TextEdit, you can use the command `open -t file.txt` or open -a: $ open -a TextEdit hi.txtto open it.
Alternatively, if TextEdit is not your default text editor, you can specifically open it in TextEdit using the command `/Applications/TextEdit.app/Contents/MacOS/TextEdit file.txt`.
Another method involves utilizing the 'open' command-line utility.
If you prefer creating aliases, you can add something like the following to your ~/.profile file: `alias textmate='open -a TextMate'` or `alias textedit='open -a TextEdit'`.
Additionally, if you have already started writing in the terminal and wish to continue in your preferred editor, you can press `ctrl+X, ctrl+E` to open it.
There is also a "quick open" option for the TextEdit content edit interface.


Question: how to fill 90% of the free memory?

Response:
To fill /dev/shm, one approach is to use the dd command.
Using ramfs is another method if it can be mounted and a large file copied to it.
For systems without /dev/shm or ramfs, writing a small C program to perform a large malloc based on an input value could be a solution.
Booting Linux with a mem=nn[KMG] kernel boot parameter is another option to run with specific memory restrictions (refer to linux/Documentation/kernel-parameters.txt for details).
The use of ulimit can help to restrict the allocatable memory for testing processes under memory constraints.
Running a virtual machine (VM) with limited memory is recommended for more efficient software testing in low memory situations.
Finally, creating a ramdisk or using tmpfs to fill RAM for testing is also an effective technique.


Question: compress a folder with tar?

Response: Use the command `tar czf name_of_archive_file.tar.gz name_of_directory_to_tar`.


Question: leaving intentional bugs in code for testers to find

Response:
Leaving intentional bugs in code for testers to find is generally considered a bad idea.
While some express a liking for the concept or believe that it is not necessarily bad, another opinion leans towards considering it difficult to do in any predictable way.
Furthermore, some find such behavior to be blatantly unethical and impractical.