Run script on a different shell than the default one

expert_vision · 03-30-2011, 03:54 PM

I need cron to run a script that manipulates huge numbers, and shell can't. So I installed bash and if I run the script from console it's ok. But when cron launch it no matter what indication I put on the first line (i.e. #!/opt/bin/bash) is still uses default shell.
Bash is on a remote location so I can't change user default shell in /etc/passwd. Besides I'm not sure of the compatibility with other shell scripts.
For instance if I run this

Code:

#!/opt/bin/bash
var=`expr 14680064000 / 1024 / 1024`
echo $var > /mnt/output

in console I get 14000
and with cron I get 2047.

p.s.:I did change shell path in crontab .. but still nothing. I even tried "screen -rms /opt/bin/bash /mnt/test" in cron. I'm clueless ...

corp769 · 03-30-2011, 03:56 PM

You can use chsh to change your default shell. To display your current shell, issue the following:

Code:

echo $SHELL

For a full list of shells on your system, do this:

Code:

chsh --list-shells

Using that, you can put the full path in your script and it will use that particular shell. Hope that helps,

Josh

expert_vision · 03-30-2011, 04:02 PM

Thx for quick reply. Apparently my linux doesn't have chsh:
-sh: chsh: not found
Actually it's a firmware with embedded linux for wl500g asus router(http://code.google.com/p/wl500g/).

expert_vision · 03-30-2011, 04:18 PM

I ended up using bc - a command line calculator .. but I would still would like to know how to run a script with a different shell .. for future scripts.

corp769 · 03-30-2011, 04:33 PM

To run a normal script with a different shell interpreter, all you need to do is change the first line of your script, as such:

Code:

#!/bin/bash

to:

Code:

#!/bin/zsh