Bash Scripting Help

[der.hans]

Am 09. Jan, 2003 schw=E4tzte Bryce C so:

> Hello all. I was wondering if anyone knew how to do an if statement in
> bash to see if results were returned?  I want to write a bash script to
> run hourly that will grep my mailbox for a certain text if the results
> are different than the contents of another, previous output, then runn
> another command.  Somethinng like:
>
> cat file|grep Text>/tmp/NewText.grep
> diff /tmp/NewText.grep /tmp/Text.grep
> if( diff returned anything ) ./runme
> mv /tmp/NewText.grep /tmp/Text.grep

The variable $? has the exit status of the last command.

$ grep -q luft /etc/passwd
$ echo $?
0
$ grep -q heisseluft /etc/passwd
$ echo $?
1

The first grep found something, the second didn't.

grep Text file > /tmp/NewText.grep
diff /tmp/NewText.grep /tmp/Text.grep >/dev/null
if [ $? -ne 0 ] ; then
=09./runme
=09mv /tmp/NewText.grep /tmp/Text.grep
fi

ciao,

der.hans
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