zsh only - This avoids the need for echo "message" | which creates an entire subshell. Also, the text you are most likely to edit is at the very end of the line, which, in my opinion, makes it slightly easier to edit.

The popular fortune program telling by a cow (see sample).

- fortune

- cowsay

Easily list all users

Filter comments and empty lines in files. I find this very useful when trying to find what values are actually set in a very long example config file.

I often set an alias for it, like :

alias nocomment='grep -v "^\($\|#\)"'

!$ recalls the last argument of the previous command. This is very useful when you have to operate several operations on the same file for example.

The $2, $3, $4 fields are arbitrary but note that the first field starts from $2 and the last field is $NF-1. This is due to the fact that the leading and trailing quotes are treated as field delimiters.

KDE4 is great, but still a bit buggy, and sometimes plasma requires to be restarted. Instead of quitting it with "killall plasma", which might loose your preferences (widgets, etc.), kquitapp will cleanly quit it. Tip: you can type this in the "Alt+F2" window, and then type "plasma" in Alt+F2 again to restart plasma (be patient though...).

See which files differ in a diff, and how many changes there are. Very useful when you have tons of differences.

I know its not much but is very useful in time consuming scripts (cron, rc.d, etc).

That "^M" is Ctrl-M, which is a carriage return, and is not needed in Unix file systems.

Where ^V is actually Ctrl-V and ^M is actually Ctrl-M (you must type these yourself, don't just copy and paste this command). ^V will not be displayed on your screen.

only works for freeBSD where ports are installed in /usr/ports

credit to http://wiki.freebsd.org/PortsTasks

The ctrl+v,ctrl+m portion represents key presses that you should do. If you do it successfully you should see a ^M character appear.

deletes first 55 lines; change the 55 to whatever number

changes the PS1 to something better than default.

[username.hostname.last-2-digits-of-ip] (current directory)

gpg command to encrypt a file on the command line.

gpg command to decrypt a previously encrypted file on the command line.

Can be optionally made into an alias:

alias decrypt='gpg --output foo.txt --decrypt foo.txt.pgp'

For quick validation of folder's file-contents (structure not taken into account) - I use it mostly to check if two folders' contents are the same.

-p PID and name of the program

-u on a UDP port.

-t also TCP ports

-o networking timer

-n numeric IP addresses (don't resolve them)

-a all sockets

show phpinfo(); from the command line

This command converts a MySQL query directly into a .csv (Comma Seperated Value)-file.

You can read, add, delete and modify Windows permissions from Linux using smbcacls from the smb-client package.