Comments on: Bourne/bash shell scripts: string comparison

By: BhupinderSingh is a layer

BhupinderSingh is a layer — Wed, 18 Nov 2009 16:20:10 +0000

You're lying. That dosen't work.
test: 40: ==: unexpected operator

By: netuddki

netuddki — Sun, 25 Oct 2009 21:59:53 +0000

The correct solution is here a year ago. It should be corrected in the article too, so one won't try those for 10 minutes before finding the answer here.

By: Florin

Florin — Thu, 16 Apr 2009 10:35:45 +0000

This is the method i curently to test if a string is empty:

if [ "X${VAR}" = "X" ]; then
echo "Empty string"
fi

Testing for equality follows the same logic but without X.

By: asd

asd — Thu, 02 Apr 2009 06:58:39 +0000

These examples don't work.

By: bhargav

bhargav — Fri, 27 Mar 2009 15:15:41 +0000

if [ "$var" = "value" ]
then
echo not the same
fi

By: Anonymous

Anonymous — Wed, 22 Oct 2008 01:38:39 +0000

i believe the $var needs to be in quotes, like so:

if [ -z "$var" ];then
echo null
fi

Best Regards,
Kibokina

By: BhupinderSingh

BhupinderSingh — Fri, 10 Jun 2005 04:43:20 +0000

this can also be used to compare 2 strings

s1 = “as”
s2 = “bs”

if test $s1 == $s2
then
echo s1 and s2 are equal
fi

By: guest

guest — Fri, 05 Mar 2004 00:35:13 +0000

the following syntax is wrong

if [ $var == "" ] ……

because if the variable $var is empty the test is
if [ == "" ] and gives an error

you are obliged to quote the var :
if [ "$var" == "" ] …

Sergio

By: Anonymous

Anonymous — Sun, 01 Feb 2004 15:47:19 +0000

Wouldn’t the following be better?

if [ -z $var ];then
echo null
fi