#!/bin/bash echo "Enter an integer; I'll test if it's really a one" read VARIABLE while [ -z "$VARIABLE" ]; do # Trap empty strings (but there's really no need!) echo "Please enter something instead of just hitting ENTER. Thank you!" read VARIABLE done # if [ "$VARIABLE" -eq "$VARIABLE" >& /dev/null ]; then # test if integer echo "'$VARIABLE' is indeed an integer" else echo "'$VARIABLE' is not an integer" fi echo "Good bye!"
Save the above in a file, say testint.sh, make it executable and test in the command line. The if statement does an arithmetic comparison which complains a lot if $VARIABLE is not an integer (that’s why there is a redirection!).