Evaluate strings as case-insensitive

gchilders · 10-13-2008, 03:12 PM

In DOS batch scripts, I used to be able to compare strings in a case-insensitive way such as:

IF /I "TEST" EQU "test" echo Matched!
IF /I "Test" EQU "test" echo Matched!

But in bash, this will always fail:

if [ "TEST" = "test" ]; then echo "Matched"; fi
if [ "Test" = "test" ]; then echo "Matched"; fi

Is there a straightforward way to make "if" evaluate the strings as case-insensitive?

Thanks,

CRC123 · 10-13-2008, 03:32 PM

the 'tr' (transform) command can do this. I don't know how the structure of your if statement is, but it seems you may be comparing two variables, so you can do a tr statement like so:

Code:

VAR1="TEST"
VAR2="test"

if [ `echo $VAR1 | tr [:upper:] [:lower:]` =  `echo $VAR2 | tr [:upper:] [:lower:]` ]; then
echo "Matches"
fi

That should do the trick.

bigrigdriver · 10-13-2008, 03:33 PM

Quote:

man bash | grep -A 4 -B 4 -i case

This will turn up references in man bash relasting to nocasematch and nocaseglob.

I'm a bit rushed now, so I'll leave it to you to research the bash man pages for more info.

colucix · 10-13-2008, 03:36 PM

Another way is to force the shell to do a case insensitive comparison:

Code:

#!/bin/bash
shopt -s nocasematch

if [[ "TEST" = "test" ]]
then
  echo "Matched"
fi

shopt -u nocasematch

shopt -s sets the option, whereas shopt -u disables it.

Edit: beaten by bigrigdriver!

gchilders · 10-13-2008, 04:27 PM

Thanks, CRC123

Your solution worked perfectly for my needed syntax:

if [ `echo $VAR1 | tr [:upper:] [:lower:]` = `echo $VAR2 | tr [:upper:] [:lower:]` ]
then CHECK=1
fi

I kind of knew I had to use tr, but couldn't quite get the syntax right. Thanks for your helpful response.