Capture output from command into variable retaining new lines

Question

I have two scripts; parentScript.sh and childScript.sh.

I want to be able to call childScript.sh inside parentScript.sh and return the errors that occur within at any stage. i.e. an error found within childScript.sh looks like:

echo "ERROR: Feed file missing for $siteTag" >&2

I know how to return the error out back towards the parent shell.

But I have a feeling it is being tampered with, I can no longer printf the result to a nice looking variable. i.e.

error+="$( { ./childScript.sh | sed 's/Output/Useless/' 2>&4 1>&3; } 2>&1 )"
error+="$( { ./childScript.sh | sed 's/Output/Useless/' 2>&4 1>&3; } 2>&1 )"

Should essentially call the script twice, get errors from both scripts and store them in the variable error as I thought, which it does but it somehow gets rid of the lines both with the use of echo "$error" or printf "$error".

Does anyone know a solution here to manage to grab error output from several commands but maintain the separate calls to echo within the childScript.sh commands?

Edit: Output should be..

ERROR: Feed file missing for (..)
ERROR: Feed file missing for (..)
ERROR: Feed file missing for (..)

But is instead

ERROR: Feed file missing for (..) ERROR: Feed file missing for (..) ERROR: Feed file missing for (..)

that other guy · Accepted Answer · 2015-08-05 15:21:39Z

2

$(..) strips trailing line feeds. This is very useful most of the time, like in

echo "Welcome to $(hostname). Enjoy your stay."

However, in your case, it ruins it a bit. You can just add one back:

error+="$( { ./childScript.sh | sed 's/Output/Useless/' 2>&4 1>&3; } 2>&1 )"$'\n'

edited Aug 5, 2015 at 15:21

answered Aug 5, 2015 at 15:20

that other guy

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3 Comments

insidesin Over a year ago

That doesn't solve it for multiple lines within one command, just multiple commands over multiple lines. :( Edit: Hang on... trying something.

that other guy Over a year ago

@insidesin Line feeds within a command are not stripped or modified. If you use echo "$error" as you say (and not echo $error or otherwise missing quotes), it's fine

insidesin Over a year ago

Ugh. I think I know what was happening. When I migrated over to another script from my test one, I brought my changes with me and then proceeded to test on real world examples... ended up testing with more command calls than error echos, so thought it when I couldn't get back to one line per error, I was having issues. I think in the end it's a case of trying to fix all at once, somehow breaking one part fixing another, etc. Thank you. :)

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