Note that the file at the given path will have the contents of the (still) deleted file, but it is a new file with a new node number; in other words, this restores the data, but it does not actually "undelete" the old file.

I posted a function declaration encapsulating this functionality to http://www.reddit.com/r/programming/comments/7yx6f/how_to_undelete_any_open_deleted_file_in_linux/c07sqwe (please excuse the crap formatting).

This runs a command continuously, restarting it if it exits. Sort of a poor man's daemontools. Useful for running servers from the command line instead of inittab.

An easy way to create aliases for moving between many directories

Long before tabbed terminals existed, people have been using Gnu screen to open many shells in a single text terminal. Combined with ssh, it gives you the ability to have many open shells with a single remote connection using the above options. If you detach with "Ctrl-a d" or if the ssh session is accidentally terminated, all processes running in your remote shells remain undisturbed, ready for you to reconnect. Other useful screen commands are "Ctrl-a c" (open new shell) and "Ctrl-a a" (alternate between shells). Read this quick reference for more screen commands: http://aperiodic.net/screen/quick_reference

I often need to add a timestamp to a file, but I never seem to remember the exact format string that has to be passed to the date command to get a compact datetime string like 20090220T231410 (i.e yyyymmddThhmmss, the ISO 8601 format popular outside the US)

mplayer -vo caca will give you a similar result but in color

instead of writing:

if [[ "$1" == "$2" ]]; then

echo "$1 is equal $2"

else

echo "$1 differs from $2"

fi

do write:

[[ "$1" == "$2" ]] && echo "$1 is equal $2" || echo "$1 differs from $2"

This finds a process id by name, but without the extra grep that you usually see. Remember, awk can grep too!

search file for string1 or string2

Pump up the chatter, run this script on a regular basis to listen to your twitter timeline.

This is a rough first cut using several cli clips I have spotted around. There is no facility to not read those things already read to you. This could also easily be put in a loop for timed onslaught from the chatterverse, though I think it might violate several pointsof the Geneva Convention

UPDATE - added a loop, only reads the first 6 twits, and does this every 5 mins.

Very entertaining when run on someone elses machine remotely ;)

On other systems, replace 'say' with the name of another text-to-speech engine, e.g. espeak ( http://espeak.sourceforge.net ) or festival ( http://www.cstr.ed.ac.uk/projects/festival )

-P displays a progress meter

-z tells rsync to use compression