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POposix shell: stdout to file, exitcode to a variable and last line of stderr to another variable
 

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  1. POposix shell: stdout to file, exitcode to a variable and last line of stderr to another variable
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    <p>I implemented the following in POSIX shell (not bash):</p> <p>fail.sh:</p> <pre><code>#!/bin/sh echo something useful echo warning 1 &gt;&amp;2 echo warning 2 &gt;&amp;2 echo an error message &gt;&amp;2 exit 100 </code></pre> <p>The command prints something I want to use on stdout, some warnings on stderr and an error message on stderr as well before failing with exit code 100.</p> <p>success.sh:</p> <pre><code>#!/bin/sh echo something useful echo warning 1 &gt;&amp;2 echo warning 2 &gt;&amp;2 exit 0 </code></pre> <p>This command prints something to stdout and some warnings to stderr but finishes successfully with exit code 0.</p> <p>test.sh:</p> <pre><code>#!/bin/sh -e script=$1 rm -f success msg=$({ $script &gt; useful; touch success; } 2&gt;&amp;1 | tail -1;) if [ -f success ]; then echo success else echo failure echo last error was: $msg fi </code></pre> <p>In this script I want to run either of those two scripts and provide the following functionality:</p> <ul> <li>the output of the scripts must be redirected to a file</li> <li>the last line of stderr must be saved to a variable so that I can print that last line later in case the command didnt exit successfully</li> <li>I want to detect whether or not the command exited successfully by checking its exit status</li> </ul> <p>My script test.sh achieves all of that but it uses an external file. Since I use <code>-e</code> the <code>touch</code> will only be executed if <code>$script</code> executed successfully. Can I capture the exit code of <code>$script</code> without this technique?</p> <p>The script must be written in POSIX shell and must use <code>-e</code>.</p>
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    1. USjosch
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    1. COWhy must it use `-e`? Is this a programming contest or homework?
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      1. USBarmar
    2. CO@Barmar neither - it is an addition to an existing shell script whose author insists on using `-e`
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      1. POposix shell: stdout to file, exitcode to a variable and last line of stderr to another variable
      1. USjosch
 

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