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Date: Thu, 06 Nov 2014 12:20:30 -0500
From: Eric van Gyzen <eric@vangyzen.net>
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To: Freebsd current <freebsd-current@freebsd.org>, jilles@FreeBSD.org
Subject: sh: "local" assignment from command loses exit status
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Jilles and -current:

In sh, if I use a single statement to declare a local variable and
assign the output of a command to it, the exit status of that command is
lost.  For example:

    should_return_false() {
        local var1=`false`
    }

The function should return non-zero, but it returns zero.  This becomes
especially apparent when using the errexit option (-e flag), since the
shell should exit, but it does not.

Splitting the declaration and assignment into two lines works around the
[suspected] bug.

A more complete example follows.

Cheers,

Eric



#!/bin/sh

returns_false() {
    var1=`false`
}

if returns_false; then
    echo 1:FAIL
else
    echo 1:PASS
fi

should_return_false() {
    local var1=`false`
}

if should_return_false; then
    echo 2:FAIL
else
    echo 2:PASS
fi

workaround_returns_false() {
    local var1
    var1=`false`
}

if workaround_returns_false; then
    echo 3:FAIL
else
    echo 3:PASS
fi

set -o errexit
trap 'echo 4:PASS' EXIT
should_return_false
trap '' EXIT
echo 4:FAIL  # because the shell should have exited