Nohup command in Shell script

nishanth_rddy · 09-21-2013, 03:34 AM

Hi

i have a below sample Shell script.

bash-3.2$ cat 1.sh
#
#
a=`ps ucx|grep -i ABC|wc -l`
if [ $a = 0 ]
then
nohup sh startprocess.sh &
echo "started process "
else
echo "process runing fine "
#
fi
bash-3.2$

this has to be setup as a crontab. if i run that script it will hang at nohup. do we have anything to Comeout of nohup.

druuna · 09-21-2013, 04:06 AM

The script doesn't hang, but waits for a carriage return. This is caused by the sh part, try this instead:

Code:

nohup /full/path/to/startprocess.sh &

unSpawn · 09-21-2013, 04:19 AM

...additionally you might mean:

Code:

COUNT=`pgrep -f ABC|wc -l`

or if you have BASH:

Code:

COUNT=($(pgrep -f ABC)); [ ${#COUNT[@]} -eq 0 ] && doSomething

where doSomething() can be defined as what druuna wrote or as

Code:

doSomething() { echo "/path/to/nohup /path/to/startprocess.sh"|/path/to/at now; }

if you have access to the (underrated and rarely mentioned) 'at' service.

jpollard · 09-21-2013, 08:53 AM

Actually, it hangs because stdout/stderr/stdin is still sent to the cron job log...

I would suggest redirecting them...

nohup sh startprocess.sh </dev/null >$HOME/logfile 2>&1 &

If "startprocess.sh" is an executable shell script then you can drop the "sh" command.

druuna · 09-21-2013, 09:18 AM

Assuming this is what you are talking about:

Code:

nohup sh startprocess.sh &

Quote:

Originally Posted by jpollard

Actually, it hangs because stdout/stderr/stdin is still sent to the cron job log...

It also "hangs" (waits for CR) when ran from the command line.

nishanth_rddy · 09-22-2013, 09:36 AM

Quote:

Originally Posted by druuna

The script doesn't hang, but waits for a carriage return. This is caused by the sh part, try this instead:

Code:

nohup /full/path/to/startprocess.sh &

Drunna even after using fullpath its hanging

bash-3.2$ ./2.sh
bash-3.2$ /usr/bin/nohup: appending output to `nohup.out'

bash-3.2$ cat 2.sh
#!/bin/bash
/usr/bin/nohup /u10/TEST/bin/startWeblogic.sh &
exit

Can you please help me ?