Re: Cron jobs, env vars, and group ID ... oh my

[Mun]

Hi Greg, Bob,

Thanks for your replies.
Please see my comments below.


On Wed, Nov 28, 2012 at 09:50 AM PST, Greg Wooledge wrote:
GW> On Wed, Nov 28, 2012 at 09:10:02AM -0800, Mun wrote:
GW> > I need to run a script via cron that in turn launches a script to set up 
the
GW> > requisite environment variables needed for a successive script that is 
called.
GW> > Moreover, I need to change my group ID in order for the scripts called 
within
GW> > the cron job to run properly.
GW> 
GW> This belongs on help-bash, not bug-bash.

Oops, my apologies; I forgot about the help-bash list.  I will post a variant
of my original post to help-bash (without this group ID problem, since you
folks have addressed that issue already).

GW> > #! /bin/bash
GW> > 
GW> > newgrp group1
GW> > id -g -n             // This shows my login group ID, not group1
GW> 
GW> Ah, the fundamental question here is "how does newgrp(1) work".

I see.  I will try Bob's suggestion to read input from another file.

Best regards,

-- 
Mun

GW> 
GW> Quoting the HP-UX man page:
GW> 
GW>       The newgrp command changes your group ID without changing your user ID
GW>       and replaces your current shell with a new one.
GW> 
GW> And a demonstration (from bash):
GW> 
GW> imadev:~$ id
GW> uid=563(wooledg) gid=22(pgmr) groups=1002(webauth),208(opgmr)
GW> imadev:~$ echo $$
GW> 8282
GW> imadev:~$ newgrp opgmr
GW> imadev:~$ echo $$
GW> 4859
GW> imadev:~$ id
GW> uid=563(wooledg) gid=208(opgmr) groups=22(pgmr),1002(webauth)
GW> imadev:~$ exit
GW> imadev:~$ echo $$
GW> 8282
GW> 
GW> So, you can see that this is utterly useless in a script.  Try using
GW> sudo(1) instead if it's available.
GW> 
GW> P.S., newgrp works very differently from within ksh, where it is a
GW> shell builtin.  Still useless in a script, though.