Periodically loop a command

while true; do ifconfig eth0 | grep "inet addr:"; sleep 60; done;
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! #/!bin/bash while true; do $1; sleep $2; done; /path/to/ "ifconfig eth0 | grep 'inet addr:'" 60
Sample Output
inet addr:  Bcast:  Mask:
[60 seconds later]
          inet addr:  Bcast:  Mask:
[60 seconds later]
          inet addr:  Bcast:  Mask:
[... Ctrl+C to stop]

By: bandit36
2009-04-01 19:29:28

What Others Think

watch -n1 -d ifconfig eth0
bartman · 524 weeks and 3 days ago
Watch equivalent: watch -n60 'ifconfig eth0 | grep "inet addr:"'
SlimG · 524 weeks and 3 days 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.
bwoodacre · 524 weeks and 3 days 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.
clockworkavian · 524 weeks and 3 days 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.
atoponce · 524 weeks and 3 days ago
while ifconfig eth0 | grep "inet addr:";do sleep 60; done;
lme · 524 weeks and 2 days 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.
TheMightyBuzzard · 524 weeks and 2 days 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; date >> downTime; done;
unixmonkey3130 · 524 weeks and 2 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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