[Xymon] function run_command in ../lib/run.c assumes sh but uses any $SHELL

[Tracy Di Marco White]

I'm using xymon 4.3.17, and server is what does the ntpdate test. Here's
the snippet of code in question:
                if (strchr(cmd, ' ') == NULL) execlp(cmd, cmd, NULL);
                else {
                        char *shell = getenv("SHELL");
                        if (!shell) shell = "/bin/sh";
                        execl(shell, "sh", "-c", cmd, NULL);
                }
                exit(127);

Note that 4.3.10 does what you say. I have that in the clients I have.

If I restart it as me, ntpdate is run, but not with an sh derivative. My
shell is tcsh, and what I start uses my environment variables. My init
script also has #!/bin/sh as the first line, but that doesn't necessarily
prevent environment variables from being inherited.
# echo $tcsh
6.18.01
# sh
# echo $SHELL
/bin/tcsh
I've added setting the shell to my startup script for now. And, to show you
what's happening, here's a snippet that echoes $SHELL:
xymon_precmd()
{
        echo $SHELL
        SHELL="/bin/sh"
        export SHELL

        touch ${xymon_pidfile} && chown ${xymon_user} ${xymon_pidfile}
}

And so, even though the startup script is run with /bin/sh, the $SHELL
variable is still set to /bin/tcsh:
# /etc/rc.d/xymon restart
Stopping xymon.
Waiting for PIDS: 29042.
/bin/tcsh
Starting xymon.
#

-Tracy


On Thu, Oct 16, 2014 at 11:43 PM, Jeremy Laidman <jlaidman at rebel-it.com.au>
wrote:

> On 17 October 2014 15:16, Tracy Di Marco White <gendalia at iastate.edu>
> wrote:
>
>> If I restart xymon while using tcsh, for example, suddenly my ntp test
>> breaks,
>>
>
> Is this a client or server?  How did you restart xymon?  My init script
> has "#! /bin/sh" in the first line, so I don't think it should matter what
> shell I run it from.
>
>
>> For the moment, I've hard coded 'export SHELL=/bin/sh' in the startup
>> script for xymon, but the assumption shouldn't be made that $SHELL is a
>> /bin/sh derivative.
>>
>
> Curiously, the code that runs the "ntpdate" command is this:
>
>   execl("/bin/sh", "sh", "-c", cmd, NULL);
>
> where "cmd" is the command (passed into the run_command() function.  So,
> I'm perplexed why it should matter what shell is running.  As far as I can
> tell, none of Xymon's binaries or scripts reference $SHELL.
>
> Cheers
> Jeremy
>
>
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