[ 2000 -ge "$(free -m | awk '/buffers.cache:/ {print $4}')" ] returns true if less than 2000 MB of RAM are available, so adjust this number to your needs.

[ $(echo "$(uptime | awk '{print $10}' | sed -e 's/,$//' -e 's/,/./') >= $(grep -c ^processor /proc/cpuinfo)" | bc) -eq 1 ] returns true if the current machine load is at least equal to the number of CPUs.

If either of the tests returns true we wait 10 seconds and check again. If both tests return false, i.e. 2GB are available and machine load falls below number of CPUs, we start our command and save it's output in a text file.

The ( ( ... ) & ) construct lets the command run in background even if we log out. See http://www.commandlinefu.com/commands/view/3115/ .

this command shows the space used in postgres directory.

the block of the loop is useful whenever you have huge junks of similar jobs, e.g., convert high res images to thumbnails, and make usage out of all the SMP power on your compute box without flooding the system.

note: c is used as counter and the random sleep

is just used as a dummy command.

This will be seen through your system's visual notification system, notify-osd, notification-daemon, etc.

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sleep accepts s,m,h,d and floats (date; sleep .25m; date)

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notify-send (-t is in milliseconds && -u low / normal / critical)

man notify-send for more information

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notification-daemon can use b/i/u/a HTML

The biggest advantage over atoponce's nifty original is not killing the scrollback. Written assuming bash, but shouldn't be terribly difficult to port to other shells. S should be multiple spaces, but I can't get commandlinefu to save/show them properly, any help?

This ran on a ubuntu box using espeak for speaking text with the bash shell. On a mac you should use 'say'. Also you can change your alarm interval and your snooze interval which are currently 8 hours and 1 minute. I would run this via cron yet it's easier to disable if you run it as a command like this :P

Requires figlet. Other than that, this should be portable enough across all the Bourne-compatible shells (sh, bash, ksh, zsh, etc).

Produces a massive number using figlet that counts down the number of seconds for any given minute interval. For example, here's a 4-minute timer:

And a 1-minute timer:

Simple countdown clock that should be quite portable across any Bourne-compatible shell. I used to teach for a living, and I would run this code when it was time for a break. Usually, I would set "MIN" to 15 for a 15-minute break. The computer would be connected to a projector, so this would be projected on screen, front and center, for all to see.

With progress bar.. hahaa this is friggin' kludge

Instead of having someone else read you the Digg headlines, Have OSX do it. Requires Curl+Sed+Say. This could probably be easily modified to use espeak for Linux.

I like much more the perl solution, but without using perl. It launches a backgroup process that will kill the command if it lasts too much.

A bigger function:

check_with_timeout() {

[ "$DEBUG" ] && set -x

COMMAND=$1

TIMEOUT=$2

RET=0

# Launch command in backgroup

[ ! "$DEBUG" ] && exec 6>&2 # Link file descriptor #6 with stderr.

[ ! "$DEBUG" ] && exec 2> /dev/null # Send stderr to null (avoid the Terminated messages)

$COMMAND 2>&1 >/dev/null &

COMMAND_PID=$!

[ "$DEBUG" ] && echo "Background command pid $COMMAND_PID, parent pid $$"

# Timer that will kill the command if timesout

sleep $TIMEOUT && ps -p $COMMAND_PID -o pid,ppid |grep $$ | awk '{print $1}' | xargs kill &

KILLER_PID=$!

[ "$DEBUG" ] && echo "Killer command pid $KILLER_PID, parent pid $$"

wait $COMMAND_PID

RET=$?

# Kill the killer timer

[ "$DEBUG" ] && ps -e -o pid,ppid |grep $KILLER_PID | awk '{print $1}' | xargs echo "Killing processes: "

ps -e -o pid,ppid |grep -v PID | grep $KILLER_PID | awk '{print $1}' | xargs kill

wait

sleep 1

[ ! "$DEBUG" ] && exec 2>&6 6>&- # Restore stderr and close file descriptor #6.

return $RET

}

Another way of counting the line output of tail over 10s not requiring pv.

Cut to have the average per second rate :

tail -n0 -f access.log>/tmp/tmp.log & sleep 10; kill $! ; wc -l /tmp/tmp.log | cut -c-2

You can also enclose it in a loop and send stderr to /dev/null :

while true; do tail -n0 -f access.log>/tmp/tmp.log & sleep 2; kill $! ; wc -l /tmp/tmp.log | cut -c-2; done 2>/dev/null

or "Execute a command with a timeout"

Run a command in background, sleep 10 seconds, kill it.

You can test it with:

find /& sleep10; kill $!

Need to have rc iso pre-downloaded before running command.

Tested with 9.10 release. Choose whatever torrent client you prefer.

This command takes a snapshot of the open files for a PID 1234 then waits 10 seconds and takes another snapshot of the same PID, it then displays the difference between each snapshot to give you an insight into what the application is doing.

Will track your mouse and save it to a file.

You can use gnuplot to graph it:

You don't want the -ar parameters in this case. The man page for BASH_BUILTINS(1) states:

"-a option means to remove or mark all jobs" and

"-r option without a jobspec argument restricts operation to running jobs"

In this case we are supplying the process id of the job to disown so neither of these should be used.

Just after you type enter, you have 3 seconds to switch window, then "texthere" will be "typed" in the X11 application that has focus. Very useful to beat your score at games such as "How fast can you type A-Z".

Press a key automatically via xvkbd.

Prerequisites: module Pod::Webserver installed. You can install it typing:

You can replace elinks with your fav browser. For FF:

If you have Firefox open, this will pop-up the index web in a new tab.

This command will play back each keystroke in a session log recorded using the script command. You'll need to replace the ^[ ^G and ^M characters with CTRL-[, CTRL-G and CTRL-M. To do this you need to press CTRL-V CTRL-[ or CTRL-V CTRL-G or CTRL-V CTRL-M.

You can adjust the playback typing speed by modifying the sleep.

If you're not bothered about seeing each keypress then you could just use:

The '[r]' is to avoid grep from grepping itself. (interchange 'r' by the appropriate letter)

Here is an example that I use a lot (as root or halt will not work):

I add the 'sleep 60' command just in case something went wrong; so that I have time to cancel.

Very useful if you are going to bed while downloading something and do not want your computer running all night.

This is a more accurate way to watch the progress of a dd process. The $DDPID=$! is needed so that you don't get the PID of the sleep. The sleep 1 is needed because in my testing at least, if you run kill -USR1 against dd too quickly, it will kill it off instead of display the status. So you need to wait a second, probably so that it can configure itself to trap the USR1 signal.

The following command will clone usb stick inside /dev/sdc to /dev/sdd

Double check you got the correct usb sticks (origional-clone)with fdisk -l.