HowTo: Set an Environment Variable in Mac OS X - Terminal Only

The process of setting environment variables in the Terminal will be familiar to those with experience with Linux or UNIX. It involves editing files in /etc for global environment variables, and in your home directory for user specific environment variables.

Login shell vs non-login shell

A login shell is the shell that is started when you open a new terminal window. A non-login shell is when you start a sub-shell in the window, for example, typing bash when you have the bash shell running already.

Global PATH only

If you just want to edit the global PATH variable, you can put a file in /etc/paths.d with the path you want to add. For example, we will create a file /etc/paths.d/ec2-api-tools and put the following in:

/etc/paths.d/ec2-api-tools

1
/opt/aws/ec2-api-tools/bin

Open a new Terminal and $PATH will reflect the change.

Bash

Setting environment variables

The format for setting an environment variable in the bash shell is KEY=value with no spaces around the equal sign. In addition, when putting it in a configuration file it is necessary to prepend it with export. The following is an example of how to set an environment variable in one of the configuration files, it also works on the command line; we will set the variable JAVA_HOME to /Library/Java/Home:

Terminal - hostname:~ user$

1
export JAVA_HOME=/Library/Java/Home

Login shell

First /etc/profile, then whichever of the following exists, trying them in order: ~/.bash_profile, ~/.bash_login, or ~/.profile

Non-login shell

/etc/bashrc, then ~/.bashrc

Have login shell read /etc/paths and /etc/paths.d

/etc/profile (Excerpt)

1
2
3
if [ -x /usr/libexec/path_helper ]; then
	eval `/usr/libexec/path_helper -s`
fi

Have login shell read /etc/bashrc and ~/.bashrc

/etc/profile (Excerpt)

1
2
3
if [ "${BASH-no}" != "no" ]; then
	[ -r /etc/bashrc ] && . /etc/bashrc
fi

~/.bash_profile (Excerpt)

1
[[ -f ~/.bashrc ]] && . ~/.bashrc

Setup /etc/profile.d

/etc/profile (Excerpt)

1
2
3
4
for sh in /etc/profile.d/*.sh ; do
        [ -r "$sh" ] && . "$sh"
done
unset sh

Terminal - hostname:~ user$

1
sudo mkdir /etc/profile.d

Resources

The following is the collection of all the changes above along with links to download them:

/etc/profile

Raw
1
2
3
4
5
6
7
8
9
10
11
12
13
14
# System-wide .profile for sh(1)

if [ -x /usr/libexec/path_helper ]; then
	eval `/usr/libexec/path_helper -s`
fi

if [ "${BASH-no}" != "no" ]; then
	[ -r /etc/bashrc ] && . /etc/bashrc
fi

for sh in /etc/profile.d/*.sh ; do
        [ -r "$sh" ] && . "$sh"
done
unset sh

/etc/bashrc

Raw
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
# System-wide .bashrc file for interactive bash(1) shells.
if [ -z "$PS1" ]; then
   return
fi

PS1='\h:\W \u\$ '
# Make bash check its window size after a process completes
shopt -s checkwinsize
# Tell the terminal about the working directory at each prompt.
if [ "$TERM_PROGRAM" == "Apple_Terminal" ] && [ -z "$INSIDE_EMACS" ]; then
    update_terminal_cwd() {
        # Identify the directory using a "file:" scheme URL,
        # including the host name to disambiguate local vs.
        # remote connections. Percent-escape spaces.
	local SEARCH=' '
	local REPLACE='%20'
	local PWD_URL="file://$HOSTNAME${PWD//$SEARCH/$REPLACE}"
	printf '\e]7;%s\a' "$PWD_URL"
    }
    PROMPT_COMMAND="update_terminal_cwd; $PROMPT_COMMAND"
fi

~/.bash_profile

Raw
1
2
3
4
5
# ~/.bash_profile

# This file is sourced by bash for login shells.  The following line
# runs your .bashrc and is recommended by the bash info pages.
[[ -f ~/.bashrc ]] && . ~/.bashrc

~/.bashrc

Raw
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
# ~/.bashrc
#
# This file is sourced by all *interactive* bash shells on startup,
# including some apparently interactive shells such as scp and rcp
# that can't tolerate any output.  So make sure this doesn't display
# anything or bad things will happen !


# Test for an interactive shell.  There is no need to set anything
# past this point for scp and rcp, and it's important to refrain from
# outputting anything in those cases.
if [[ $- != *i* ]] ; then
        # Shell is non-interactive.  Be done now!
        return
fi


# Put your fun stuff here.

Tcsh

Setting environment variables

For the tcsh shell, the format for setting an environment variable is setenv KEY value. The following is an example which will set the JAVA_HOME variable to /Library/Java/Home.

Terminal - [hostname:~] %

1
setenv JAVA_HOME /Library/Java/Home

Login shell

First /etc/csh.cshrc, then /etc/csh.login, then whichever of the following exists, trying in order: ~/.tcshrc, ~/.cshrc; then finally ~/.login.

Non-login shell

First /etc/csh.cshrc, then whichever of the following exists, trying in order: ~/.tcshrc, ~/.cshrc.

References

Parts of this series