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Periodically loop a command

Terminal - Periodically loop a command
while true; do ifconfig eth0 | grep "inet addr:"; sleep 60; done;
2009-04-01 19:29:28
User: bandit36
Functions: grep ifconfig sleep
Periodically loop a command

You can use this to loop any command to periodically see the output.

while true; do [YOUR COMMAND HERE]; sleep [# of seconds]; done;

Alternatively, you can put it in a simple shell script to save typing!


while true; do $1; sleep $2; done;

/path/to/script.sh "ifconfig eth0 | grep 'inet addr:'" 60


There are 4 alternatives - vote for the best!

Terminal - Alternatives

Know a better way?

If you can do better, submit your command here.

What others think

watch -n1 -d ifconfig eth0

Comment by bartman 473 weeks and 1 day ago

Watch equivalent:

watch -n60 'ifconfig eth0 | grep "inet addr:"'
Comment by SlimG 473 weeks and 1 day ago

Yeah, use watch, if it is available. The best part is that the -d option allows highlighting of the things that have changed since the last invocation. watch is part of the base ubuntu install and comes from the 'procps' package.

Comment by bwoodacre 473 weeks and 1 day ago

Alternatively, there's another really cool alternative to while: until, which negates the condition:

until false;do sleep 1;done

Which actually is handy for things like pinging a down machine

until ping -c1 machine;do sleep 1;done;beep

will make a beep when the machine is back up.

Comment by clockworkavian 473 weeks and 1 day ago

@SlimG- two things: 1) you don't need to nest the command. 2) if you insist on nesting it, for the love of everything good and holy, ditch the backticks.

Comment by atoponce 473 weeks and 1 day ago
while ifconfig eth0 | grep "inet addr:";do sleep 60; done;
Comment by lme 473 weeks and 1 day ago

@atoponce: 1) yes you do or grep won't fire until watch exits. 2) those aren't backticks, they're single quotes; quite different.

Comment by TheMightyBuzzard 473 weeks ago

I used it to check my connection since I have some troubles with my ISP (yeah I know I could change...). I put time and date in a file every time my connection is down like this:

while true; do ping pong.sunet.se; date >> downTime; done;
Comment by unixmonkey3130 473 weeks ago

Your point of view

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