nohup means no hang-up. This command allows Linux processes to continue running in the background even after logging out or closing the terminal. This is very useful for running long-duration scripts. Today we will learn how to use the nohup command to run shell script in background without interruptions.
Table of Contents
Run Shell Script in Background with NOHUP :
Suppose you have a shell script named test.sh that executes a long-running task:
#!/bin/sh
echo "Task starts"
sleep 120
echo "Task ends"
To run this script in background , use below :
nohup sh test.sh &
Output :
nohup: ignoring input and appending output to 'nohup.out'
[1] 12345
nohup.outstores the command’s output unless we give any log file name .[1] 12345represents the background job ID (1) and the process ID (12345).
Store the Output to a Custom Log File :
By default, nohup writes output to nohup.out. You can redirect output to a specific log file:
nohup sh test.sh > test.log 2>&1 &
> test.logredirects standard output totest.log.2>&1redirects standard error to the same log file.
Check Running Processes with nohup :
To verify if the script is running, use below :
ps -ef| grep test.sh
or,
ps -ef| grep nohup
Or, check background jobs in the current session :
jobs
Stop/kill a NOHUP Process :
Terminate it using the PID :
kill -9 <PID>
So, now you can understand how to use the nohup command to run shell script in background. Also you can get more information from the below Doc as well.
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