Commands by OJM (4)

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Delete all but latest file in a directory
Useful for deleting old unused log files.

Fix VirtualBox error

stop man page content from disappearing on exit
stop man page content from disappearing on exit echo "export LESS='FiX'" >> ~/.bashrc man bash 'q'uit out of man page content will stay on screen

Insert a line at the top of a text file without sed or awk or bash loops
Just use '-' to use STDIN as an additional input to 'cat'

Generate random number with shuf
If you don't have seq or shuf, bash can be used.

Do command when logged in from certain ips using ssh
Place in ~/.bashrc If you login to a ssh server from different ips, sometimes you want to do something specific for each. e.g., quickly go into screen -x session from a phone, but not your desktop.

Decrypt MD5
Decrypt MD5 , replace 1cb251ec0d568de6a929b520c4aed8d1 with the MD5 string you want to decrypt

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

convert (almost) any image into a video
This is an extract from a larger script which makes up slideshow videos from images. $seconds is the number of seconds the video will last, and $num is a loop counter which numbers the videos for concat into a longer video later, so they will be in order. The dev/null bit on the end cuts ffmpeg's verbosity.

nmap IP block and autogenerate comprehensive Nagios service checks
More info here: http://nagioswiki.com/wiki/index.php/Autocreating_Nagios_Configuration_with_Nmap_and_Nmap2Nagios.pl


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