UNIX for Dummies Questions & Answers

if [ "$ext" -eq "cpp" ] || [ "$ext" -eq "h" ] || [ "$ext" -eq "js" ]; then

ext=h
case $ext in
cpp|h|js)   echo "Do this" ;;
ph|php|lua) echo "Do that" ;;
*) echo "Do anything else" ;;
esac

declare -a lang=(cpp sql js h py)
if [[ ${lang[@]} =~ "$ext" ]]; then

$ ext=pp
$ if [[ ${lang[@]} =~ "$ext" ]]; then echo hello; fi
hello

declare -a lang=(cpp sql js h)
if [[ ${lang[@]} =~ $(echo "\<${ext}\>") ]]; then

$ ext=cpp; if [[ ${lang[@]} =~ $(echo "\<${ext}\>") ]]; then echo hello; fi
$

$ cat show_ext.sh 
#!/bin/bash

ext=cpp
declare -a extentions=(cpp sql js h)
if [[ ${extentions[@]} =~ $(echo "\<${ext}\>") ]]; then
    echo Hello $ext
fi

ext=pp
declare -a extentions=(cpp sql js h)
if [[ ${extentions[@]} =~ $(echo "\<${ext}\>") ]]; then
    echo Hello $ext
fi

$ bash show_ext.sh 
Hello cpp

$ bash --version
bash --version
GNU bash, version 4.1.2(1)-release (x86_64-redhat-linux-gnu)