Use an environment variable in a launchd script

Solution 1:

Not in the ProgramArguments key. You need to add an EnvironmentVariables key into your plist's dict like so:

<?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>EnvironmentVariables</key>
    <dict>
           <key>AN_ENVIRONMENT_VARIABLE_NAME</key>
           <string>the_value</string>
    </dict>
    <key>Label</key>
    <string>me.mpietz.MountDevRoot</string>
    <key>ProgramArguments</key>
    <array>
        <string>/bin/sh</string>

        <string>$HOME/bin/attach-devroot.sh</string>

        <!-- Instead of using...
        <string>/Users/mpietz/bin/attach-devroot.sh</string -->
    </array>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>

See: Creating Launch Daemons and Agents.

Solution 2:

The best way to handle this is by wrapping your command in a shell. For example:

<?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>KeepAlive</key>
    <false/>
    <key>Label</key>
    <string>sh.daniel.envvar</string>
    <key>ProgramArguments</key>
    <array>
        <string>/bin/zsh</string>
        <string>-c</string>
        <string>echo 'You did the thing!' > $HOME/did-the-thing.log</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>

❯ cat ~/did-the-thing.log
You did the thing!

The flag -c tells ZSH (and Bash, and sh) to run the command specified in your next. If you add the flag -l, it’ll load your dotfiles before executing, just as a normal login shell does.

Solution 3:

I don't think launchd knows about the environment natively, at least not as ${VARIABLE} substitutions.

There's nothing stopping you from launching a shell script (or a shell with -c) as your launchd action though, and that would have an environment and respect ${VARIABLES} -- Be aware of the difference between System and User daemons/agents in that case though...

Solution 4:

I'm not sure - I haven't tried it before... but I can tell you that if the only variable you care about is home - you can use ~.

So: <string>~/bin/attach-devroot.sh</string>