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Print stack trace of a core file without needing to enter gdb interactively
The pstack command prints a stack trace of running processes without needing to attach a debugger, but what about core files? The answer, of course, is to use this command. Usage: gdbbt program corefile

Get a regular updated list of zombies
to omit "grep -v", put some brackets around a single character

display information about the CPU

Generate a random password 30 characters long
According to the gpg(1) manual: --gen-random 0|1|2 count Emit count random bytes of the given quality level 0, 1 or 2. If count is not given or zero, an endless sequence of random bytes will be emitted. If used with --armor the output will be base64 encoded. PLEASE, don't use this command unless you know what you are doing; it may remove precious entropy from the system! If your entropy pool is critical for various operations on your system, then using this command is not recommended to generate a secure password. With that said, regenerating entropy is as simple as: $ du -s / This is a quick way to generate a strong, base64 encoded, secure password of arbitrary length, using your entropy pool (example above shows a 30-character long password).

Vectorize xkcd strips
Uses ImageMagick and potrace to vectorize the input image, with parameters optimized for xkcd-like pictures.

Ultimate current directory usage command
Based on the MrMerry one, just add some visuals and sort directory and files

Log the current memory statistics frequently to syslog
Uses logger in a while loop to log memory statistics frequently into the local syslog server.

Stores the certificate expiration date on the variable A
Stores the certificate expiration date on the variable A

list files recursively by size

Find longest running non-root processes on a machine
If you have ever been trying to look for a list of processes based on their elapsed time you don't need to look any further. This command lets you find the list of processes ordered in a reversed order (oldest at the top) that have been running for over an hour on your system. Any system processes are filtered out, leaving only user initiated ones in. I find it extremely useful for debugging and performance analysis.


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