How do you parse a variable in a bash script?

Shell Programming and Scripting
1

I have a script I use on my web server (Apache2). I am changing to Lighttpd and need to make a few changes.

This is what I use on my apache server

#!/bin/bash
# accepts 3 parameters: <domain name> <user name> <XXXXXXXX>
# domain name is without www (just domain.com)
# username would be best at 6 - 10 chars long
# only checks if last is present and uses it for MySQL
# password. If not present - does not create mysql account
if [ "$3" != "" ]; then

--- snip ----

useradd $2 -m
filename=/etc/apache2/sites-available/$2.www
echo "<VirtualHost 10.10.10.10>" > $filename
echo "ServerAdmin webmaster@$1" >> $filename

--- snip some more -----

I now need to parse the first variable to add some characters:

So basically:

using example.com

#
# example.com
#
$HTTP["host"] =~ "(^|\.)example\.com$" {
server.document-root = "/home/example/public_html"
server.errorlog = "/var/log/lighttpd/example-error.log"
accesslog.filename = "/var/log/lighttpd/example-access.log"
server.error-handler-404 = "/e404-example.php"
}

Needs to become:

echo "#" >> $filename
echo "# %1" >> $filename
echo "#" >> $filename
echo "$HTTP[\"host\"] =~ \"(^|\.)<domain>\.<tld>$\" {" >> $filename
--- etc ----

I think the best way would be to parse until I hit the period and use the first part as one variable and the last part as another. I hope this makes sense.
Any assistance would be appreciated.

Alan

2

So something like this?

#!/bin/bash

domain=${1%.*}
tld=${1#*.}

cat <<HERE
#
# $domain.$tld
#
\$HTTP["host"] =~ "(^|\.)$domain\.$tld\$" {
server.document-root = "/home/$domain/public_html"
server.errorlog = "/var/log/lighttpd/${domain}-error.log"
accesslog.filename = "/var/log/lighttpd/${domain}-access.log"
server.error-handler-404 = "/e404-$domain.php"
}
HERE

Example run:

vnix$ /tmp/htt example.com
#
# example.com
#
$HTTP["host"] =~ "(^|\.)example\.com$" {
server.document-root = "/home/example/public_html"
server.errorlog = "/var/log/lighttpd/exampleerror.log"
accesslog.filename = "/var/log/lighttpd/example-access.log"
server.error-handler-404 = "/e404-example.php"
}

I hope I got all the details right.

You can't really "parse" the variables much, you can perform simple string substitutions like I have but basically it's just $1 $2 $3 and if you need anything fancier, use some external utility.

3

Thanks for the fast reply! The more I learn about BASH the more I realize I have to learn.

I'll try it out right now.

4

That does exactly what I needed. Again MANY thanks!