Bash: execute command

Ephracis · 08-03-2007, 03:16 PM

I am writing a script that will run a gcc command. I want the script to stop executing if the gcc command fails and output something like "script failed" and then just stop.

Is there a way in bash to execute a command and catch errors from it in an if-then-else or something?

Thanks!

jailbait · 08-03-2007, 03:27 PM

"Is there a way in bash to execute a command and catch errors from it in an if-then-else or something?"

Yes. Check the gcc return code within an if statement. Normal completion gives a return code of zero. An error gives a non-zero return code. You can even get fancy and take different actions based on which error code is returned.

-----------------
Steve Stites

krizzz · 08-03-2007, 03:28 PM

Basically you need to check the value of exit code of gcc, using $? variable. Non-zero result means error.

Ephracis · 08-03-2007, 04:26 PM

Thanks! The $? was exactly what I was looking for. I googled a lot for "command execution return" and stuff but couldn't find a place that said "the return code of the command is in $?" :P

Thanks! That helped a lot.

jlliagre · 08-03-2007, 04:45 PM

Or this simpler solution:

Code:

...
gcc ... || { echo gcc failed ; exit ; }
...

theNbomr · 08-03-2007, 06:20 PM

or

Code:

make

--- rod.

Ephracis · 09-01-2007, 07:54 AM

make would require me to create a makefile. This script is supposed to compile, create an xml file, pack into a tar and move for installation. So..

paulsm4 · 09-02-2007, 10:04 PM

So, like - what's wrong with having the *makefile* create the XML, pack it into a tar file, and move it for installation?

I would argue that a makefile (or, in some environments, Maven or Ant) would be the *better* (simpler, more robust, more flexible) solution!

IMHO .. PSM

Ephracis · 10-07-2007, 08:23 AM

Now you have really triggered my interest. Can Makefile do all that? I am currently using CMake as the build system for my project. Is there a way to create such wonderful Makefiles via CMake?

Please enlighten me.

Tischbein · 10-07-2007, 10:58 AM

Ah, that signature just got me going! Here's a third way of doing it:

Code:

#!/bin/bash

cry_murder()
{
  if (($? != 0))
  then
      printf "%s\n" \
             "Would you like to take a seat and have a cup of nice" \
             "relaxing green tea.  I have some bad news for you..." \
            >&2
  fi
}

trap cry_murder 0   # Execute cry_murder on exit
set -e              # If any command returns an error value, exit

echo beg to differ | grep stuff  # No stuff, so grep returns 1.

echo That went just swell.       # Never executed