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exit if another instance is running
runs only one instance.

Discover the process start time
That is useful to discover the start time of process older than 1 day. You can also run: $ ls -ld /proc/PID That's returning the creation date of the proc files from the process. Some users reported that this way might show you a wrong date since any other process like cron, for example, could change this date.

Encrypted chat with netcat and openssl (one-liner)
client$ while true; do read -n30 ui; echo $ui |openssl enc -aes-256-ctr -a -k PaSSw ; done | nc localhost 8877 | while read so; do decoded_so=`echo "$so"| openssl enc -d -a -aes-256-ctr -k PaSSw`; echo -e "Incoming: $decoded_so"; done This will establish a simple encrypted chat with AES-256-CTR using netcat and openssl only. More info here https://nixaid.com/encrypted-chat-with-netcat/

Check general system error on AIX
Check general system error on AIX

Monitor a file's size
use "watch" instead of while-loops in these simple cases

Force an fsck on reboot
Force an fsck on reboot. Useful on a system where / has mounted read-only because of file system issues.

burn a isofile to cd or dvd
cdrecord must be installed. usefull alias: $alias burniso='cdrecord -v dev=/dev/cdrom' now iso burning is like. $burniso image.iso

whowatch: Linux and UNIX interactive, process and users monitoring tool
whowatch is a interactive, ncurses-based, process and users monitoring tool, which updates information in real time. This is a perfect tool for local and remote servers. It displays information about the users currently logged on to the machine, in real-time. Besides standard information (login name, tty, host, user's process), the type of the connection (ie. telnet or ssh) is shown. Display of users command line can be switch to tty idle time. Certain user can be selected and his processes tree may be viewed as well as tree of all system processes. Tree may be displayed with additional column that shows owner of each process. In the process tree mode SIGINT and SIGKILL signals can be sent to the selected process. Killing processes is just as simple and fun as deleting lines on the screen.

function to compute what percentage of X is Y? Where percent/100 = X/Y => percent=100*X/Y
This function make it easy to compute X/Y as a percentage. The name "wpoxiy" is an acronym of "what percentage of X is Y"

open a screenshot of a remote desktop via ssh
standard image viewers do not seem to be able to open a FIFO file. xloadimage was the first one i've stumbled upon that can handle this.


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