Exit script with error code based on loop operations in bash

Question

I have a wrapper script for a CI pipeline which works great, but it always returns with 0 even though subcommands in a for loop fails. Here is an example:

#!/bin/bash

file_list=("file1 file2 file_nonexistant file3")

for file in $file_list
do
  cat $file
done

>./listfiles.sh
file1 contents
file2 contents
cat: file_nonexistant: No such file or directory
file3 contents
>echo $?
>0

Since the last iteration of the loop is successfull the entire script exits with 0. What i want is for the loop to continue on fail and for the script to exit 1 if any of the loop iterations returned errors.

What i have tried so far:

• set -e but it halts the loop and exits when an iteration fails
• replaced done with done || exit 1 - no effect
• replaced cat $file with cat $file || continue - no effect

Answer 1

Alternative 1

#!/bin/bash

for i in `seq 1 6`; do
    if test $i == 4; then
        z=1
    fi
done
if [[ $z == 1 ]]; then
  exit 1
fi

With files

#!/bin/bash

touch ab c d e
for i in a b c d e; do
    cat $i
    if [[ $? -ne 0 ]]; then
        fail=1
    fi
done

if [[ $fail == 1 ]]; then
    exit 1
fi

The special parameter $? holds the exit value of the last command. A value above 0 represents a failure. So just store that in a variable and check for it after the loop.

The $? parameter actually holds the exit status of the previous pipeline, if present. If the command is killed with a signal then the value of $? will be 128+SIGNAL. For example 128+2 in case of SIGINT (ctrl+c).

Overkill solution with trap

#!/bin/bash

trap ' echo X $FAIL; [[ $FAIL -eq 1 ]] && exit 22 ' EXIT

touch ab c d e
for i in  c d e a b; do
    cat $i || export FAIL=1
    echo F $FAIL
done