Bash

musther · 02-07-2008, 04:36 PM

I've got a script which needs to test for the presence of certain programs, for example zenity.

Anyway, I'm testing like this:

Code:

echo -n "zenity             "
	zenity --help >> /dev/null
		if [ "$?" != "0" ]; then
			echo -en "\033[1;31m"
			echo "NOT FOUND"
			echo -e "\033[0m"
			ZOK=1
			OK=1
		else
			echo -en "\033[1;32m"
			echo "PRESENT"
			echo -e "\033[0m"
			ZOK=0
		fi

Obviously I don't want any output from zenity, so I'm using >> /dev/null to get rid of that. But if zenity isn't installed I still get the output.

Code:

bash: zenity: command not found

How can I suppress this output, so whether zenity is there or not, nothing is output on the command zenity --help

Thanks

acid_kewpie · 02-07-2008, 04:41 PM

if you're already redirecting the stdout, just send stderr to stdout too...

Code:

# command_which -doesnt work 2>&1 > /dev/null
#

jlliagre · 02-08-2008, 07:05 AM

With all due respect, acid_kewpie's answer has a couple of issues.

Here is something that should do better:

Code:

type zenity >/dev/null 2>&1
if [ "$?" != "0" ]; then
...

acid_kewpie · 02-08-2008, 07:21 AM

i was only looking at the stderr redirection. not the best way to check for a working application. But since when was i due respect?

pixellany · 02-08-2008, 07:52 AM

Quote:

But since when was i due respect?

29,000 posts ought to be good for something......

jlliagre · 02-08-2008, 07:55 AM

Quote:

Originally Posted by acid_kewpie

i was only looking at the stderr redirection.

You should have reversed the redirection order for this to work. That was the first issue.

Quote:

not the best way to check for a working application.

Yes, the error wasn't sent by the command but by the shell, defeating stderr redirection goal.

Quote:

But since when was i due respect?

Everyone is due respect, especially mods with such a number of posts

And I wouldn't have liked my own posting to be reported

JWPurple · 02-08-2008, 08:47 PM

Code:

if [[ -x zenity ]]
then
   echo "PRESENT"
else
   echo "MISSING"
fi

is much easier.

musther · 02-08-2008, 09:48 PM

Well it's easier so long as you know the path to zenity, and you know that will be consistent.

Thanks for all the advice, I have it working now (by redirecting stderr).