Using "nice" on a script

[smolloy]

I've got a script that I run as a cron job, and I'd like to drop its priority using "nice". Can I just call the entire script with "nice", or should I edit the script to call each of its internal functions with nice?

In other words,

less /usr/local/sbin/sysupdate.sh

#!/bin/bash
nice /usr/bin/emerge --sync
nice /usr/bin/emerge -uDN --world

Then just call /usr/loca/sbin/sysupdate.sh normally, or remove all the "nice" statements in the script and call it like this,

nice /usr/local/sbin/sysupdate.sh

[anomie]

Can I just call the entire script with "nice", or should I edit the script to call each of its internal functions with nice?

You don't need the nice statements within the script (assuming you want the script and all its children processes to have the same nice value). The children will inherit niceness from the parent.

Example:

[ceyan@troy ~]$ cat some-script.bash 
#!/bin/bash
./some-child.bash &
sleep 100
exit 0

[ceyan@troy ~]$ cat some-child.bash 
#!/bin/bash
sleep 100
exit 0

[ceyan@troy ~]$ nice -n 12 ./some-script.bash & 
[1] 22949

[ceyan@troy ~]$ ps -eo pid,comm,ni | head -1 && ps -eo pid,comm,ni | grep 'some-'
  PID COMMAND           NI
22949 some-script.bas   12
22950 some-child.bash   12

As demonstrated here, both the parent and child have the same nice value of 12.

[smolloy]

Thanks anomie. Calling the entire script with "nice" will give all child functions the same nice value, just as I want.

Thanks.