Seq allows you to define printf like formating by specified with -f, %03g is actually tells seq I got three digits, fill the blank digits with 0, and the range is from 176 to 240.

strace can be invaluable in trying to figure out what the heck some misbehaving program is doing. There are number of useful flags to limit and control its output, and to attach to already running programs. (See also 'ltrace'.)

You cannot kill zombies, as they are already dead. But if you have too many zombies then kill parent process or restart service.

You can kill zombie process using PID obtained from the above command. For example kill zombie proces having PID 4104:

# kill -9 4104

Please note that kill -9 does not guarantee to kill a zombie process.

This is priceless for discovering otherwise invisible characters in files. Like, for example, that stray Control-M at the end of the initial hash bang line in your script, which causes it to generate a mysterious error even though it looks fine.

('od' is the last word, of course, but for many purposes it's much harder to read.)

Just type 2 characters and enter, you will be back.

This is a quick and dirty way to generate a (non-floating-point) CPU-bound task to benchmark. Adjust "20" to higher or lower values, as needed. As a benchmark this is probably a little less bogus than bogomips, and it will run anywhere 'bc' does.

get my GPG-key from pgp.surfnet.nl, key id is 19886493.

my $.02

You need sudo privileges for this command.

Replace username with actual username.

Reverts the changes that were made in a particular revision, in the local working copy. You must commit the local copy to the repository to make it permanent.

This is very useful for undoing a change.

You can revert multiple changes by specifying numbers wider apart; Just remember to put the highest number first.

Makes a partition in ram which is useful if you need a temporary working space as read/write access is fast.

Be aware that anything saved in this partition will be gone after your computer is turned off.

syntax follows regular command line expression.

example: let's say you have a directory (with subdirs) that has say 4000 .php files.

All of these files were made via script, but uh-oh, there was a typo!

if the typo is "let's go jome!" but you meant it to say "let's go home!"

find . -name "*.php" | xargs perl -pi -e "s/let\'s\ go\ jome\!/let\'s\ go\ home\!/g"

all better :)

multiline: find . -name "*.php" | xargs perl -p0777i -e 's/knownline1\nknownline2/replaced/m'

indescriminate line replace: find ./ -name '*.php' | xargs perl -pi -e 's/\".*$\"/\new\ line\ content/g'

k add principle

If you spend all day editing in vi then switching your fingers to Emacs mode just for the command line can be difficult. Use set -o vi in your bash shell and enjoy the power of a real editor.