[Linuxcommand-discuss] regular expressions in scripts

[Mertens B. <bra...@li...>]

Hi,

I'm trying to figure out how to perform a regular expression as the
expression for an if-statement:

I want it to either strip the trailing / if it's present or add it if it
isn't.

I thought the second would be easier since it wouldn't require creating
a substring but I can't get it to work! I've tried for over an hour
yesterday using every expression I could think of!

Here's the if-statement:
if [ ! "expr $2 match'.*/$'" ]; then
        TARGET_DIR=$2/
	echo "target dir changed to ${TARGET_DIR}"
fi

Some of the things I tried are 
[ ! $2 = .*/$ ]
[ ! $2 : .*/$ ]
[ ! "expr $2 ='.*/$'" ]
[ ! "expr $2 match'.*/$'" ]
[ ! "${2}" = "*/$" ] and [ ! "${2}" = ".*/$" ]
with no quotes, double quotes, single quotes, brackets, etc.
I've also tried with and without spaces after the ":" or "=" or
"match"...

Part of the problem is that I don't know what the correct regular
expression is. Sometimes you ".*" sometimes it's just "*" (not to
mention quotes and brackets!)

I found something about pattern matching in a reference book called
"Linux in a nutshell" but I can't find examples.

Should anybody have this book it's in table 4-17 (at least in my
translated version).  These are the 4 possibilities:
${VAR#PATTERN}
${VAR##PATTERN}
${VAR%PATTERN}
${VAR%%PATTERN}

If I understand it correctly I would need something like:
${${2}%/} but I get "bad substitution"

Any suggestions?

TIA
-- 
|          Mertens Bram "M8ram"  <bra...@li...>
|   Registered [Red Hat] Linux User # 249103 since Octobre 2000
| http://linux.be | http://www.redhat.com | http://counter.li.org
 \____________________________