Shell Programming and Scripting

...or use regex(bash only)...

Code:

if [[ "$zone" =~ ^([4567]|10|11|20|21|23|25)$ ]]; then
        zonecheck=1
else
        echo "That's not a region"
fi
#
# Alternate, not so efficient way in ksh 
# if echo "$zone" | grep -qE '^([4567]|10|11|20|21|23|25)$' ; then

The if statement:

Code:

if [[ $zone =~ ^[4567]|10|11|20|21|23|25$ ]]; then
        zonecheck=1
else
        echo "That's not a region\n"
fi

does not work in bash. The 1st anchor only anchors the 1st alternative in that RE and the last anchor only anchors the last alternative in that RE. So, with both bash and 1993 or later versions of ksh, that if statement will accept zones 79, 125, 110, 239, and lots of others that should not be accepted. If you use the same ERE that you used in the grep -E command, both recent versions of bash and 1993 or later versions of ksh give the correct results for all expansions of $zone that do not contain any embedded whitespace characters. A test that would work in either of those shells for any settings of the zone variable would be:

Code:

if [[ "$zone" =~ ^([4567]|10|11|20|21|23|25)$ ]]; then
        zonecheck=1
else
        printf "That's not a region\n\n"
fi

Note that depending on operating systems and shell options, the command:

Code:

echo "That's not a region\n"

will either print the string That's not a region\n followed by a single <newline> character or the string That's not a region followed by two <newline> characters. I used printf instead of echo to be sure that you get the output I think you wanted no matter which operating system, version of the shell, and shell options you're using.