I have written a shell script that I want to run every time I log on to my Macbook, and I'm trying to execute it via launchd.

My script is not a persistent daemon, it's supposed to write some text to a file and then be done until my next login.

This is the plist I created for it, which plutil -lint pronounces OK:

    
        Label
        com.example.test
        Program
        /Users/Tom/Desktop/tomtest.sh
        KeepAlive
        
        OnDemand
        
        LaunchOnlyOnce
        
        StandardOutPath
        /Users/Tom/Desktop/tomtest.log
        StandardErrorPath
        /Users/Tom/Desktop/tomtest.log
        Debug
        
    

I copied it to ~/Library/LaunchAgents/com.example.test.plist and did sudo chown to give it to root:wheel. Shortly after doing so, I got a system notification telling me about this new service; I did not capture the text to share here, but it seemed normal (i.e. a good sign). And, when I open System Settings > General > Login Items & Extensions, I see my script:

Here is the entirety of the shell script tomtest.sh:

#!/bin/sh

echo "I ran" > /Users/Tom/Desktop/tomtest.log
exit 0

Despite logging out and in again, the log file doesn't even exist. So I manually created it (touch) and retried, but still no dice.

When I run the script manually from the CLI, it writes text to the log file as expected.

I've been trying to debug/fix this using launchctl, but I keep getting this error:

~ $ launchctl bootstrap gui/501 com.example.test
Bootstrap failed: 5: Input/output error
Try re-running the command as root for richer errors.

~ $ sudo launchctl bootstrap gui/501 com.example.test
Password:
Bootstrap failed: 5: Input/output error

Here is the relevant output of launchctl print gui/501:

disabled services = {
    "com.apple.ManagedClientAgent.enrollagent" => disabled
    "com.example.OLDtest" => enabled
    "com.apple.Siri.agent" => disabled
    "com.apple.FolderActionsDispatcher" => enabled
    "com.apple.appleseed.seedusaged.postinstall" => disabled
    "com.apple.ScriptMenuApp" => disabled
}

My com.example entry is there, but (1) it is listed, confusingly, as "enabled" within the "disabled" block, and (2) it has an old name. The old name is from a previous version of the plist file that had a typo in the name, but that version of the service also never worked. And I have never seen the new version appear, despite having a different filename and Label. com.example does not appear anywhere else in the ~2000 lines of output.

When I run launchctl load ~/Library/LaunchAgents/com.example.test, I get no output and no error, but the log file is still blank.

Why am I getting "Bootstrap failed: 5: Input/output error" from such a simple program?

In case I've got an X/Y problem here: my real goal is not to write to a log file; I have written a zsh script that generates new desktop wallpaper for me every day, and the script I really want to run will generate the PNG file and then use osascript to actually change the desktop wallpaper. It works when I run it from the CLI.

So, my goal is not to launch a persistent service such as a DB server. I want macOS to run my script once every time I log in, which could be several times per day, and each time I expect my script to take about 2 seconds and then exit 0. My research suggests that the launchd system is the best tool for this, but I am open to other suggestions that are equally invisible -- I will not accept the "Open at Login" because it opens the Terminal app to execute my script.

I am the only user of this machine.

M4 Macbook Air running macOS Sequoia 15.5