Setting Apache2 PATH environment variable

Question

How can you set the PATH environment variable for Apache2? I've tried setting it in /usr/sbin/envvars and in httpd.conf with SetEnv PATH (and passing it along to SSI with PassEnv), but it just doesn't get carried along.

Answer 1

As others have said, you do this through use of the an environment variable file. I will provide more details in this answer, and show proof that it works.

This environment variable file must be source from apachectl. On my Ubuntu box, this file is at /etc/apache2/envvars. On RedHat, this is at /etc/sysconfig/httpd. On FreeBSD, this is set in /etc/rc.conf (I think). As an alternative, you can also set this information in a startup script (/etc/init.d/httpd or apachectl, etc.). However, I think it's best to leave the startup scripts alone if possible. The best place is in the designated environment variables script.

1. Verify the location of this envvars file. On Ubuntu, /etc/init.d/apache2ctl shows that it sources /etc/apache2/envvars:

   # the path to the environment variable file
   test -z "$APACHE_ENVVARS" && APACHE_ENVVARS='/etc/apache2/envvars'
   # pick up any necessary environment variables
   if test -f $APACHE_ENVVARS; then
      . $APACHE_ENVVARS
   fi
   

2. To view the variables, I am using a Perl printenv.cgi script, and made it available at http://example.org/cgi-bin/printenv.cgi . The script shows me the following PATH:

   PATH = /usr/local/bin:/usr/bin:/bin
   

3. To change these variables, I edit the envvars file:

   $ sudo vim /etc/apache2/envvars 
   

4. Modify your PATH in this file. In this example, I will append /opt/local/bin to my PATH. In some cases, you may need to use export PATH and not just PATH:

   export PATH=$PATH:/opt/local/bin
   

5. Restart apache

   $ sudo service apache2 restart
    * Restarting web server apache2
    ... waiting    ...done.
   $
   

6. View the results on http://example.org/cgi-bin/printenv.cgi , which now show that the PATH now contains a new element:

   PATH = /usr/local/bin:/usr/bin:/bin:/opt/local/bin
   

If the above does not work, something unusual may be happening happening. Perhaps your script is ignoring or overwriting the PATH.

Answer 2

On my system it's /etc/apache2/envvars.

Answer 3

Make sure you've loaded mod_env.

The correct syntax is (example):

SetEnv LD_LIBRARY_PATH /usr/local/lib

This worked for me.

Answer 4

On my Apache2 system I found that a lot of visitors only wanted to pillage my carefully-compiled collection of Smileys/emoticons (seriously!), so I decided to use a randomly-generated symlink to the directory path that would be picked up as an Apache2 variable, and it was practically impossible to share links.

So, every 30 minutes, cron ran a perl script that would rewrite the .htaccess file and include a SetEnv as you can see below:

....
SetEnv SMILEYDIR "QyQGTZ8cgcK3zMVL0aNJ"

Then, at the top of my PHP pages I'd read the variable like so, and later in the page there'd be that variable used to build a path to the apprpropriate smiley:

$SMILEYDIR = apache_getenv("SMILEYDIR");
....
....
echo '<img src="/'.$SMILEYDIR.'//SMILEY_yay!.gif" border="0" hspace="3">';

Works for me, and hope it helps you!

Answer 5

You can set it in start() function of init script, something like this:

start() {
        echo -n $"Starting $prog: "
        check13 || exit 1
        export PATH=${PATH}:/var/ossec/bin
        LANG=$HTTPD_LANG daemon --pidfile=${pidfile} $httpd $OPTIONS
        RETVAL=$?
        echo
        [ $RETVAL = 0 ] && touch ${lockfile}
        return $RETVAL
}

Create a Perl script to list all the environment variables:

#!/usr/bin/perl -wT
print "Content-type: text/html\n\n";

foreach $key (sort keys(%ENV)) {
  print "$key = $ENV{$key}<p>";
}

Place it into /var/www/cgi-bin, and check http://domain.com/cgi-bin/env.cgi, you will see the belows:

PATH = /sbin:/usr/sbin:/bin:/usr/bin:/var/ossec/bin