Re: [MLUG] basic Unix pipe/exit code problem

[ryan woodsmall <EMAIL:PROTECTED>]

>> In bash you can check the last program's return code using the 
>> variable $?.  In tcsh, you can use $status.
>
> Would this be something Mark could use?

Depends.  In a lot of my scripts, I do something like the following:

###BEGIN###

     #!/bin/bash
     cmd1 | cmd2 | grep SOMETHING >/dev/null 2>&1
     if [ $? == 0 ] ; then
         echo found SOMETHING
         exitcode=0
     else
         if [ $? == 1 ] ; then
             echo did not find SOMETHING
             exitcode=1
         fi
     fi
     exit $exitcode

###END###

Hopefully this will format correctly.

This pipes commands together (cmd1 > cmd2 > grep), suppressing output.  
The return code of  the final command (in this case, grep) is checked 
and preserved and an appropriate message is printed out.  Finally, the 
program exits with the last command's exit value.  Bash's value 
checking has to be nested because it's strictly if/then/else, not 
if/then/else if/else.  Kind of ugly, but it works.

This is something I use all the time, but this isn't a real example - 
you'd have to build on it.

   ryan woodsmall
     EMAIL:PROTECTED

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