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Find usb device in realtime
Using this command you can track a moment when usb device was attached.

disable caps lock
a quick one-line way to disable caps lock while running X.

Make a playlistfile for mpg321 or other CLI player
A short variant if you have only one directory whit only audio files in it.

Short one line while loop that outputs parameterized content from one file to another
There is a common command for outputting a field or list of fields from each line in a file. Why wouldn't you just use cut?

Convert a script to one-liner
Opposite: Convert an one-liner to script: $ foo() { ; } ... $ typeset -f foo ... $ unset -f foo

diff files while disregarding indentation and trailing white space
**NOTE** Tekhne's alternative is much more succinct and its output conforms to the files actual contents rather than with white space removed My command on the other hand uses bash process substitution (and "Minimal" Perl), instead of files, to first remove leading and trailing white space from lines, before diff'ing the streams. Very useful when differences in indentation, such as in programming source code files, may be irrelevant

Rename .JPG to .jpg recursively
Recursively rename .JPG to .jpg using standard find and mv. It's generally better to use a standard tool if doing so is not much more difficult.

Add temporary entry to authorized_keys
If you frequently need to connect to your ubersecure mainframe from various uberunsafe machines, you have to face difficult decision: (a) type the password everytime during the session (lame), (b) add local public key to mainframes authorized_keys file (unsafe), (c) as above, but remove this key at the end of the session (pain in the a55). So let's say you save The Command to tempauth file in bin directory of your mainframe's account and make it executable. Then, while you're on one of these unsafe ones, do: $ cat $HOME/.ssh/id_rsa.pub|ssh 5z474n@mainframe.nl bin/tempauth 30 and password prompts stop the harassment for 30 minutes and you don't have to care to remove the unsafe key after that.

Run a file system check on your next boot.
The empty file /forcefsck causes the file system check fsck to be run next time you boot up, after which it will be removed. This works too: $sudo >/forcefsck

Capture all plaintext passwords


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