Scenario / Questions

We just got our new server(s) up and we’re running CentOS on them all. After successfully installing Ruby Enterprise Edition, I would now like to add the REE /bin (located at /usr/lib/ruby-enterprise/bin) directory to make it the default Ruby interpreter on the server.

I have tried the following, which only adds it to the current shell session:

export PATH=/usr/lib/ruby-enterprise/bin:$PATH

What would be the correct approach to permanently adding this directory to $PATH for all users. I am currently logged in as root.

Thanks in advance!

Find below all possible solutions or suggestions for the above questions..

Suggestion: 1

It’s not a good idea to edit /etc/profile for things like this, because you’ll lose all your changes whenever CentOS publishes an update for this file. This is exactly what /etc/profile.d is for:

# echo 'pathmunge /usr/lib/ruby-enterprise/bin' > /etc/profile.d/ree.sh
# chmod +x /etc/profile.d/ree.sh

Log back in and enjoy your (safely) updated PATH:

# echo $PATH
/usr/lib/ruby-enterprise/bin:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
# which ruby
/usr/lib/ruby-enterprise/bin/ruby

Instead of logging back in, you could reload the profile:

# . /etc/profile

This will update the $PATH variable.

Suggestion: 2

After following fmonk’s advice I checked out /etc/bashrc, where I noticed it said that “Environment stuff goes in /etc/profile.” I proceeded to look in /etc/profile, I saw this:

pathmunge () {
    if ! echo $PATH | /bin/egrep -q "(^|:)$1($|:)" ; then
       if [ "$2" = "after" ] ; then
          PATH=$PATH:$1
       else
          PATH=$1:$PATH
       fi
    fi
}

[...]

# Path manipulation
if [ "$EUID" = "0" ]; then
    pathmunge /sbin
    pathmunge /usr/sbin
    pathmunge /usr/local/sbin
fi

To solve my problem, I simply added pathmunge /usr/lib/ruby-enterprise/bin underneath the if statement. This solved my issue.

Suggestion: 3

“An interactive login shell is started
after a successful login, using
/bin/login, by reading the /etc/passwd
file. This shell invocation normally
reads /etc/profile and its private
equivalent ~/.bash_profile upon
startup.

An interactive non-login shell is
normally started at the command-line
using a shell program (e.g.,
[prompt]$/bin/bash) or by the /bin/su
command. An interactive non-login
shell is also started with a terminal
program such as xterm or konsole from
within a graphical environment. This
type of shell invocation normally
copies the parent environment and then
reads the user’s ~/.bashrc file for
additional startup configuration
instructions.”
http://www.linuxfromscratch.org/blfs/view/6.3/postlfs/profile.html

Therefore I would not put environment variables in bashrc, because it is not only against common convention, but you will also miss your bashrc varialbles when invoking a terminal from a graphical Desktop environment.

On Redhat in the /etc/profile I found this comment:

“System wide aliases and functions should go in /etc/bashrc. Personal
environment variables and startup programs should go into
~/.bash_profile. Personal aliases and functions should go into
~/.bashrc.”

So if you want to set environment variables on a user basis, do it in the user’s .bash_profile file.

Heading over to the .bash_profile I read:

“Personal environment variables and startup programs.

Personal aliases and functions should go in ~/.bashrc. System wide
environment variables and startup programs are in /etc/profile.
System wide aliases and functions are in /etc/bashrc.”

Conclusion
If you want only root to see programs residing, for instance in /sbin I would add that path to root’s .bash_profile file. But if you want every user to see what root specific programs are installed on your box I would put /sbin into /etc/.profile. Now every user can use tab completion to look for root specific programs and elevate rights if necessary.

Special Case: SSH
When ssh is started with a commandline, an interactive login shell is started. But in this case /etc/profile is not read. When I defined environment variables in the .bash_profile file of each user it worked with ssh.

Suggestion: 4

SORRY misinterpretted the question
the following asnwer is for a USER’s profile
leaving it in case it helps someone

modify .bash_profile

nano ~/.bash_profile

then somewhere in the file add/modify your paths seperated by :

 PATH=$PATH:$HOME/bin:/your/path
 export PATH

then reload your profile

source ~/.bash_profile

or logout and login again

if you check PATH it should include your newly added paths

echo $PATH

Suggestion: 5

You can set environment variables in a .rc file; for bash shells (I believe the most common, and default in CentOS) each user has a file called .bashrc in his home directory.

Add the command PATH=/usr/lib/ruby-enterprise/bin:$PATH to this file to set it for any one particular user.

To set it for all users (as you mention), change it in /etc/bashrc (the default .bashrc in each user’s home directory should source this file, but you should doublecheck that).