Friday, August 30, 2013

Bash : Wait for a command with timeout

Here is a very useful little command that wait for a process to finish and kill it if doesn't exit after a pre defined timeout.

The command is called timeout and is part of the coreutils package witch is embedded by default in CentOS 6.

Usage is very simple, you just need to specify the timeout, the process to start and optionally the signal to send in case of failure.

Timeout returns the exit value of the process and if the timeout has been reached, the value 124 is returned.

Here are some examples on how to use timeout :

Successful process : 
 $ timeout 10s ls /tmp  
 $ echo $?  

Unsuccessful process :
 $ timeout 10s ls /blabla  
 ls: cannot access /blabla: No such file or directory  
 $ echo $?  

Timed out process :
 $ timeout 5s sleep 10  
 $ echo $?  

More details in the man page.

Hope that helps !

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