bash: set exit status without breaking loop?

Question

I am writing bash script to check the fstab structure.

In a for loop, I have placed a return statement to use the exit code later in the script, but it seems that the return statement is breaking the loop after printing the first requested output

How can I assign a return code of 1 without breaking the loop so I will get all the results and not just the first?

for i in $(printf  "$child"|awk '/'$new_mounts'/'); do

    chid_count=$(printf  "$child"|awk '/'$new_mounts'/'|wc -l)

    if [[ $chid_count -ge 1 ]]; then
        echo -e "\e[96mfstab order check failed: there are child mounts before parent mount:\e[0m"
        echo -e "\e[31mError: \e[0m "$child"\e[31m  mount point, comes  before \e[0m $mounts \e[31m on fstab\e[0m"
        return 1
    else
        return 0
    fi
done

...btw, '/'$new_mounts'/' is very, very wrong -- it string-splits the contents of new_mounts rather than passing it to awk as part of a single argument. "/$new_mounts/" would be an improvement. Consider passing your code through shellcheck.net, and reading mywiki.wooledge.org/Quotes closely. — Charles Duffy
– Charles Duffy, Commented Mar 7, 2016 at 18:19
...similarly, any shell where echo -e does anything other than print -e on its output is out of compliance with the POSIX sh standard -- see the POSIX spec for echo at pubs.opengroup.org/onlinepubs/009604599/utilities/echo.html. Consider using printf instead, which allows a standards-compliant, portable tool for comparable tasks. — Charles Duffy
– Charles Duffy, Commented Mar 7, 2016 at 18:20
Tempted to flag as duplicate of stackoverflow.com/questions/35533501/… but I'll just repeat what I wrote in my answer there: use Awk. — tripleee
– tripleee, Commented Mar 7, 2016 at 18:25
@tripleee, ...that is, indeed, a very on-point answer for the larger problem (as opposed to the immediate language-level question). — Charles Duffy
– Charles Duffy, Commented Mar 7, 2016 at 22:16
@Max_il, ...btw, also, for i in $(...) is actually not the best tool for the job when your goal is to iterate over lines of output. See mywiki.wooledge.org/DontReadLinesWithFor, and/or mywiki.wooledge.org/BashFAQ/001 (for something with a focus on the best-practice approach). — Charles Duffy
– Charles Duffy, Commented Mar 7, 2016 at 22:18

Charles Duffy · Accepted Answer · 2016-03-07 18:17:09Z

1

If you read the documentation for the language, immediately returning is what return is supposed to do. That's not unique to shell -- I actually can't think of a single language with a return construct where it doesn't behave this way.

If you want to set a value to be used as a return value later, use a variable:

yourfunc() {
  local retval=0

  for i in ...; do
    (( child_count >= 1 )) && retval=1
  done

  return "$retval"
}

answered Mar 7, 2016 at 18:17

Charles Duffy

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2 Comments

chepner Over a year ago

Haskell's return doesn't :)

Charles Duffy Over a year ago

@chepner, Haskell guarantees order of operation between statements at all? That's not as purely functional as I'd expect. :)

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