Running two loops simultaneously in bash - bash

Question

I am reading file in which two different types of key-value pairs are there and I have to pass those key-value pairs to another file. For that I have to run two loops which doesn't seems me the optimized approach. Below the code I am trying and it will also clarify you what I am trying to do :
#!/bin/bash
set -e
# Prints command usage
function usage() {
cat <<EOF
Usage: $0 [--in-file <infile>] [--env <env>]
EOF
}
env=""
# Parse Args
POSITIONAL=()
while [[ $# -gt 0 ]]; do
key="$1"
case $key in
-i|--in-file)
in_file=$2
shift 2 # past argument and value
;;
-e|--env)
env="$2"
shift 2 # past argument and value
;;
*) # unknown option
echo "unknown option"
shift # past argument
;;
esac
done
set -- "${POSITIONAL[#]}" # restore positional parameters
if [[ ${in_file} == "" ]]; then
echo "ERROR: Missing in-file argument"
usage
exit 1
fi
cat ${in_file}
echo "Unsilencing alarms"
declare -A summary
overall_status_failed="false"
silence_ids=`yq read -j ${in_file} alarm_ids | jq -M -r .[]`
while read -r silence_id; do
echo "Unsilencing ${silence_id} silence id"
if [env != ""]; then
./unsilence_alarm.sh --alarm-id ${silence_id} --env ${env}|| script_failed="true"
else
./unsilence_alarm.sh --alarm-id ${silence_id}|| script_failed="true"
fi
if [[ "${script_failed}" == "true" ]]; then
summary["silence id ${silence_id} "]='Fail'
overall_status_failed="true"
script_failed="false"
else
summary["silence id ${silence_id} "]='Pass'
fi
done <<< "${silence_ids}"
echo "Unsilencing moody alarms"
silence_ids=`yq read -j ${in_file} moody_alarm_ids | jq -M -r .[]`
while read -r silence_id; do
echo "Unsilencing ${silence_id} moody silence id"
if [env != ""]; then
./unsilence_alarm.sh --moody-alarm-id ${silence_id} --env ${env}|| script_failed="true"
else
./unsilence_alarm.sh --moody-alarm-id ${silence_id}|| script_failed="true"
fi
if [[ "${script_failed}" == "true" ]]; then
summary["moody silence id ${silence_id}"]="Fail"
overall_status_failed="true"
script_failed="false"
else
summary["moody silence id ${silence_id}"]="Pass"
fi
done <<< "${silence_ids}"
set +x
echo
echo
echo
echo +------------------------- Unsilence summary --------------------------+
for status in "${!summary[#]}"; do
printf "${status} - ${summary[$status]}\n"
done
echo +----------------------------------------------------------------------+
if [[ "${overall_status_failed}" == "true" ]]; then
exit 1
fi
exit
Can anyone tell me the optimized approach for merging these two while loops? Another file accepts the parameters like:
[--alarm-id <id>] [--moody-alarm-id <id>] [--env <env>]

Answer 1

Combine both while blocks with the help of associative arrays and wrap it in for
Does this work as expected?
...
declare -A flags
flags[alarm_ids]="--alarm-id"
flags[moody_alarm_ids]="--moody-alarm-id"
for alarm_id in alarm_ids moody_alarm_ids; do
silence_ids=`yq read -j ${in_file} ${alarm_id} | jq -M -r .[]`
while read -r silence_id; do
echo "Unsilencing ${silence_id} silence id"
./unsilence_alarm.sh ${flags[$alarm_id]} ${silence_id} ${env:+"--env ${env}"} \
|| script_failed="true"
if [[ "${script_failed}" == "true" ]]; then
summary["silence ${flag[alarm_id]//-/ } ${silence_id} "]='Fail'
overall_status_failed="true"
script_failed="false"
else
summary["silence ${flag[alarm_id]//-/ } ${silence_id} "]='Pass'
fi
done <<< "${silence_ids}"
done
...
Simultaneous would not be easy. If you do need it, wrap the above code snippet in a function without the for loop; and use a parameter to pass the "key" to the the while loop. And then you could start them as background activities with foo &. But that would not make it easier for summary. Since you need to wait for it to complete anyway - synchronous is the way to go.
Also ${env:+"--env ${env}"} expands to the rhs of + if lhs (env) is not null. Using 4-statement long if-else block seemed tedious. I am not sure if this method is frowned upon, but this is how I personally would have done it.