Bash arrays and case statements - review my script

```
#!/bin/bash
# Change the environment in which you are currently working.
# Actually, it calls the relevant 'lettus.sh' script

if [ "${BASH_SOURCE[0]}" == "$0" ]; then
echo "Try running this as \". chenv $1\""
exit 0
fi

usage(){
echo "Usage: . ${PROG} -- Shows a list of user-selectable environments."
echo " . ${PROG} [env] -- Select environment."
echo " . ${PROG} -h -- Shows this usage screen."
return
}

showEnv(){
# check if index0 exists, assume we have at least the first (zeroth) element
#if [ -z "${envList}" ]; then
if [ -z "${envList[0]}" ]; then
echo "array \$envList is empty! " >&2
return 1
fi

# Show all elements in array (0 -> n-1)
for i in $(seq 0 $((${#envList[@]} - 1))); do
echo ${envList[$i]}
done
return
}
setEnv(){
if [ -z "$1" ]; then
usage; return
fi

case $1 in
cold) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_cold.sh;;
coles) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_coles.sh;;
fc) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_fc.sh;;
fcrm) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_fcrm.sh;;
stable) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_stable.sh;;
tip) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_tip.sh;;
uat) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_uat.sh;;
wellmdc) FILE_TO_SOURCE=/u2/tip/conf/ctrl/lettus_wellmdc.sh;;
*) usage; return;;
esac

if $IS_SOURCED; then
echo "Environment \"$1\" selected."
echo "Now sourcing file \"$FILE_TO_SOURCE\"..."
. ${FILE_TO_SOURCE}
return
else
return 1
fi
}

main(){
if [ -z "$1" ]; then
showEnv; return
fi

case $1 in
-h) usage;;
*) setEnv $1;;
esac
return
}

PROG="chenv"

# create array of user-selectable environments
envList=( cold coles fc fcrm stable tip uat wellmdc )

main "$

In showEnv, why do you need to check that envList is empty when you define it right in the program?

I'd write the array elements one-per-line with:

# Show all elements in array
for elem in "${envList[@]}"; do 
    echo "$elem"
done

or, more succinctly

printf "%s\n" "${envList[@]}"

In setEnv:

case $1 in
    cold|coles|fc|fcrm|stable|tip|uat|wellmdc)
        FILE_TO_SOURCE="/u2/tip/conf/ctrl/lettus_$1.sh" ;;
    *)  usage; return;;
esac

or, without duplicating the contents of envList:

FILE_TO_SOURCE=""
for elem in "${envList[@]}"; do
    if [ "$elem" = "$1" ]; then
        FILE_TO_SOURCE="/u2/tip/conf/ctrl/lettus_$1.sh"
        break
    fi
done
if [ -z "$FILE_TO_SOURCE" ];then 
    usage
    return
fi

You might want to check that the relevant file exists

if [ ! -f "$FILE_TO_SOURCE" ]; then
    echo "missing config file '$FILE_TO_SOURCE'!"
    echo "contact $maintainer for assistance"
    return 1
fi

What is $IS_SOURCED? You might want to document how that environment variable is defined.

You don't need the return at the end of main or at the end of the program.

StackExchange Code Review Q#12520, answer score: 5