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I'm trying to learn how to write portable shell scripts, to do so I'm starting to migrating my personal utilities from bash to sh (dash on my system). There is however a error I'm getting in all cases when I try to run the scripts in debugging mode $ dash -x script

For instance, on this script:

#!/bin/sh
echo hi

If I run it as: $ dash script, I get the 'hi' string, however if I run it as: $ dash -x script or if I add the set -x command before echo:

#!/bin/sh
set -x
echo hi

It fails with the error:

script.sh: 3: script.sh: Bad substitution

this makes very difficult to debug my scripts. I'm running ubuntu 12.04 with dash 0.5.7-2ubuntu2

Javier López
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  • Possible duplicate of [String replacement in bash - bad substitution error](http://stackoverflow.com/questions/8960677/string-replacement-in-bash-bad-substitution-error) – kenorb Jul 12 '16 at 22:19

1 Answers1

3

Just by the time I finished writing my question I realized I was using a personalized PS4 (which is used in xtrace mode), my PS4 was defined as:

>>(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }

I changed temporarily as PS4=">>" and everything went ok, I can now debug my scripts on dash. Hope this helps someone.

Javier López
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