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Print process run time, average CPU usage, and maximum memory usage on exit
Bash has a built-in time command which provides less functionality than the real time command. Thus we reference /usr/bin/time directly. Since the command isn't very easy to remember you could alias it to something like "cputime" or even just "time".

Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

Batch resize all images in the current directory that are bigger than 800px, height or weight.
You need to install imagemagick. On Debian type: # apt-get install imagemagick

Big (four-byte) $RANDOM
Sometimes, in a shell script, you need a random number bigger than the range of $RANDOM. This will print a random number made of four hex values extracted from /dev/urandom.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Move files around local filesystem with tar without wasting space using an intermediate tarball.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

resume other user's screen session via su, without pty error
Normally, if you su to another user from root and try to resume that other user's screen session, you will get an error like "Cannot open your terminal '/dev/pts/0' - please check." This is because the other user doesn't have permission for root's pty. You can get around this by running a "script" session as the new user, before trying to resume the screen session. Note you will have to execute each of the three commands separately, not all on the same line as shown here. Credit: I found this at http://www.hjackson.org/blog/archives/2008/11/29/cannot-open-your-terminal-dev-pts-please-check.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Google Translate
Usage: $ translate Example: $ translate hello en es See this for a list of language codes: http://en.wikipedia.org/wiki/List_of_ISO_639-1_codes


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