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create random numbers within range for conjob usage
if you need to install cron jobs in a given time range.

Find the package that installed a command

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"

Resets your MAC to a random MAC address to make you harder to find.
Next time you are leaching off of someone else's wifi use this command before you start your bittorrent ...for legitimate files only of course. It creates a hexidecimal string using md5sum from the first few lines of /dev/urandom and splices it into the proper MAC address format. Then it changes your MAC and resets your wireless (wlan0:0).

Killing processes with your mouse in an infinite loop
Useful for quickly cleaning your Desktop. Nice joke if launched at startup.

full memcache client in under 255 chars (uses dd, sed and nc)
usage: mem memcache-command [arguments] where memcache-command might be: set add get[s] append prepend replace delete incr decr cas stats verbosity version notes: exptime argument is set to 0 (no expire) flags argument is set to 1 (arbitrary)

validate json
I have this saved as jsonlint chmodded +x and file.js is instead $1, but YMMV

determine if tcp port is open
Requires netcat.

How to run a command on a list of remote servers read from a file
The important thing to note in this command, is the "-n" flag.

Daemonize nc - Transmit a file like a http server
Allow to launch nc like a daemon, in background until you still stop it. You can stop it with kill %1 (jobs method) or kill PID. The -k option can force nc to listen another connection, but if you use redirection, it will work only one time. The loop's inside doesn't do anything, but we can imagine to send a message to screen when a connection is established


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