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quickly backup or copy a file with bash

Revert back all files currently checked out by Perforce SCM for edit

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"

Count the frequency of every word for a given file
Counts the frequency of words in a file

Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

Continuously listen on a port and respond with a fixed message with netcat (and respond to kill signals)
`while true`: do forever `nc -l -p 4300 -c 'echo hello'`: this is the but anything can go here really `test $? -gt 0 && break`: this checks the return code for ctrl^c or the like and quite the loop, otherwise in order to kill the loop you'd have to get the parent process id and kill it.

Quickly generate an MD5 hash for a text string using OpenSSL
Thanks to OpenSSL, you can quickly and easily generate MD5 hashes for your passwords. Alternative (thanks to linuxrawkstar and atoponce): $ echo -n 'text to be encrypted' | md5sum - Note that the above method does not utlise OpenSSL.

Colored SVN diff
Simple way to achieve a colored SVN diff

Export a subset of a database
Limits the number of rows per table to X

HDD Performance Write Test
Test your XFS filesystem and Raptor hard drives for write performance.


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