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How do you set an environment variable on startup so that it can be used in applications?

For example, ATOM_HOME is used by Atom.

  • What method do you use to start atom? Which version for the app and which build / version for macOS. – bmike Aug 31 '18 at 21:21
  • I start it from the application bundle, and use High Sierra. – 0az Sep 3 '18 at 23:12
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Solution

The solution uses two files: environment.plist and environment.conf.

environment.plist should be placed in ~/Library/LaunchAgents for a per user solution (recommended), or in /Library/LaunchAgents for a global solution (not recommended – potential security loophole).

environment.conf can be placed almost anywhere. $PATH_TO_ENVIRONMENT_CONF can be relative, but only to the 'default' environment variables, or any that are defined in a EnvironmentVariables key. 1

environment.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>local.launchd.environment</string>
  <key>ProgramArguments</key>
  <array>
    <string>sh</string>
    <string>-c</string>
    <string>xargs -L 1 launchctl &lt; $PATH_TO_ENVIRONMENT_CONF</string>
  </array>
  <key>RunAtLoad</key>
  <true/>
</dict>
</plist>

environment.conf:

setenv ATOM_HOME $HOME/.config/atom
setenv SOME_VAR "Use quotes if spaces are necessary"

How it works

When a user logs in, the LaunchAgents in ~/Library/LaunchAgents are executed. In this case, sh -c xargs -L 1 launchctl < $PATH_TO_ENVIRONMENT_CONF is executed. launchctl manages daemons and agents. In this case, we are using it to set an environment variable accessible to all applications and the shell.

xargs -L 1 launchctl &lt; $PATH_TO_ENVIRONMENT_CONF

xargs                     # xargs converts stdin to command line arguments
xargs -L 1                # Tells xargs to invoke launchctl for each line
           launchctl      # Run launchctl with the arguments
                     &lt; # Since a plist is an xml document, angle brackets must be escaped. 

                     &lt; $PATH_TO_ENVIRONMENT_CONF
                          # This tells xargs to read input from the file at $PATH_TO_ENVIRONMENT_CONF

This solution can also be extended to other launchctl subcommands.

  • 1
    Doesn't seem to work in High Sierra. – Justin Lardinois Aug 31 '18 at 20:43
  • Still works for me. – 0az Sep 3 '18 at 23:11

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