All commands

When expanding, bash output the command, so don't be affraid if you type the command.

Here is the details:

First examples:

First argument:

echo barfoo

barfoo

(Note that typing echo foo bar foobar barfoo && echo !$, bash substitute !$ with $:1)

Last argument:

echo foo bar foobar barfoo && echo barfoo

foo bar foobar barfoo

barfoo

All the arguments:

echo foo bar foobar barfoo

foo bar foobar barfoo

The third argument:

echo foo bar foobar barfoo && echo foobar

foo bar foobar barfoo

foobar

You may want to add {} for large numbers: echo !:{11} for example

Now with path:

/usr/bin/foobar

For the head:

echo /usr/bin

/usr/bin

And the tail:

echo foobar

foobar

You also may want to try !:h and !:t or !!3-4 for the third and the fourth (so !!:* == !!:1-$)

tar options may change ;)

c to compress into a tar file, z for gzip (j for bzip) man tar

-print0 and -0t are usefull for names with spaces, \, etc.

seq allows you to format the output thanks to the -f option. This is very useful if you want to rename your files to the same format in order to be able to easily sort for example:

And

foo1

foo10

foo4

foo7

But:

So

foo01

foo04

foo07

foo10

this will find text in the directory you specify and give you line where it appears.

/proc/cpuinfo contains information about the CPU.

Search for "processor" in the /proc/cpuinfo file

wc -l, counts the number of lines.

grep -sq "" filename && command

grep can be used in combination with && to run a command if a file exists.

This commands lets you generate a random number between the range [$START; $END].

The trick here is to use the brackets [ ] around any one of the characters of the grep string. This uses the fact that [?] is a character class of one letter and will be removed when parsed by the shell. This is useful when you want to parse the output of grep or use the return value in an if-statement without having its own process causing it to erroneously return TRUE.

Using process substitution, we can 'trick' tee into sending a command's STDOUT to an arbitrary number of commands. The last command (command4) in this example will get its input from the pipe.

Files saved on a windows machine use different ascii characters for lines turns. When viewing such files in VI the will most often have a ^M(control-VM) character at the end of each line. This command will remove all occurrences of that character

zsh only

I always hated resorting to using $(seq -w 1 99) to pad numbers. zsh provides a shortcut that couldn't be more intuitive. It also works in reverse {99..01}

zsh only

If you have this command in your history, you can always re-run it and have it reference the latest file.

The glob matches all timestamped files and then the resulting array is sorted by modification time (m) and then the first element in the sorted array is chosen (the latest)

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