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Q: How do I do a su -c "command" so that bash comes out as the default shell. ( Answered,   0 Comments )
Subject: How do I do a su -c "command" so that bash comes out as the default shell.
Category: Computers > Operating Systems
Asked by: cheekoo1-ga
List Price: $10.00
Posted: 22 Jan 2004 13:32 PST
Expires: 21 Feb 2004 13:32 PST
Question ID: 299071
please answer only with regards to total description.

I need to "su" to a given user name whose default shell is "tcsh", but
use a "bash" shell to execute a few shell scripts/commands which are
written in "bash" and not in "tcsh".(Due to paucity of time and lack
of experience I cannot convert them into "tcsh" from "bash".)

I cannot use su -c <username> -s <shell name> option, because my
version of solaris does not allow me the "-s" option.

In effect I am trying to call something like this :

    $build_cmd = ("su amazon -c \"bash -c \"cd $AMAZON/buildfwrk/bin; source boo; ant usage\"\" > " ."`/opt/admin/bin/newlogf

system ($build_cmd);

But given the number of double quotes I have to use, I am not sure
whether the above given command will really work.Please give me the
code, if you are suggesting that I write a shell script to do the
Subject: Re: How do I do a su -c "command" so that bash comes out as the default shell.
Answered By: haversian-ga on 22 Jan 2004 22:03 PST
Good evening cheekoo1-ga,

If solaris prevents you from specifying a shell using -s, perhaps you
can use bash to solve your problem.

What I mean is that bash accepts arguments, one of them being a file
to use in lieu of standard input.

So, your command could read
   su amazon -c "bash /home/jrandomuser/commands.txt"

This way, the one command that su allows you to run is bash.  So far,
so good.  Next you need to get bash to run commands.  You simply put
them in a file, one command per line, exactly as you would type them
at the commandline, and save that file somewhere accessible by user
amazon.  Then, have bash execute that file, and you're good to go.

For you, this means putting
   cd $AMAZON/buildfwrk/bin; source boo   [... - your lines got truncated oddly]

in a file somewhere (say /home/jrandomuser/commands.txt) readable by
user amazon.  In fact, since you're no longer limited to one line, you
can separate your commands more legibly with returns than ;s.  Then
execute the su command I gave above.

When bash finishes with the file, it encounters the EOF, which causes
it to terminate.  This drops you back to tcsh, but (on my Linux
system) does not end your su session.  Solaris may behave differently.
 If you need this tested, I do have access to Solaris machines
(Sol/Sparc, not Solx86) at university.

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