Sometimes commands are long, but useful, so it's helpful to be able to make them permanent without having to retype them. An alternative could use the history command, and a cut/sed line that works on your platform.

finding all files with the metadata tag "data" using the metadata find command mdfind , writing the list to a temporary file, reading the input for the .zip file from this temporary file.

Converts a .pdf to .jpg . should work with jpeg | tiff | png | gif | jp2 | pict | bmp | qtif | psd | sgi | tga

I use this on debian testing, works like the other sorted du variants, but i like small numbers and suffixes :)

If you want a password length longer than 6, changing the -c6 to read -c8 will give you 8 random characters instead of 6. To end up with a line-feed, use this with echo:

# echo `< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c6`

Cleanly create tempfiles using mktemp and remove them using traps instead of removing them in the end of the script. This way, you make sure the tempfiles are removed properly even if the script is killed or interrupted.

For a user script in KDE4, you can set TMPROOT using :

A key sequence for terminating a frozen session. Full sequence on a swedish keyboard: [ENTER] [ALTGR] tilde [SPACE] dot

requires mplayer

Scans the file once to build a list of line numbers that contain non-printable characters

Scans the file again, passing those line numbers to sed as two commands to print the line number and the line itself. Also passes the output through a tr to replace the characters with a ?

copies all files from the source disk / (skipping boundaries of mouted -in volumes) to /mnt/mydisk. Logical links are being preserved as well as devices, pipes etc. This can copy a MacOS X or Linux volume and keep it bootable. Note: its not suited to copy files with MacOS 9 style resources.

Someone might attack on your system. You can drop attacker IP using IPtables. However, you can use route command to null route unwanted traffic. A null route (also called as blackhole route) is a network route or kernel routing table entry that goes nowhere. Matching packets are dropped (ignored) rather than forwarded, acting as a kind of very limited firewall. The act of using null routes is often called blackhole filtering.

Gets the latest Tweets in your friends timeline from Twitter. Uses curl and xmlstarlet.

Uses curl, xmlstarlet and festival to speak your horoscope. Modify the m (month) and d (day) parameters to the astrology web service to hear your personal horoscope.

Will search recursively and output the searchResult.txt in the same folder you are located.

Pick a mp3 at random and play it.

Assumes the availability of locate with an updated db and mpg123

Not the most useful command I guess, but all of the really useful ones are taken...

This command is very helpful when we need to duplicate a test scenario and first we want to find out the installed libraries together with the version and release numbers and architecture. (look example)

Command can be tuned by choosing just the names of libraries we are interested in. For example glibc and gcc.

this will increase the volume by 2 decibels on the pcm channel. the argument to -c is for which sound card to use, the arg after set is the channel (PCM, Master, etc.) and what to set by.

related commands:

amixer -c 0 set PCM 2dB-

decrease volume by 2 decibels

amixer -c 0 set PCM toggle

toggle mute/unmute

this is for alsa systems

for mac os (and maybe other UNIX systems) osascript -e 'set Volume *' where * is any number (can have decimal points) between 0 and 10