How can I debug a Launchd script that doesn't run on startup?

Question

I have some Launchd scripts from homebrew. However I have to manually run them when I restart my computer:

launchctl load -w ~/Library/LaunchAgents/com.mysql.mysqld.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>KeepAlive</key>   <true/>   <key>Label</key>   <string>com.mysql.mysqld</string>   <key>Program</key>   <string>/Users/dash/.local/Cellar/mysql/5.1.49/bin/mysqld_safe</string>   <key>RunAtLoad</key>   <true/>   <key>UserName</key>   <string>dash</string>   <key>WorkingDirectory</key>   <string>/Users/dash/.local/var</string> </dict> </plist> 

I thought this should happen on startup. What am I missing?

Answer 1

Best way I found to debug, in your plist:

<key>StandardErrorPath</key> <string>/tmp/mycommand.err</string> <key>StandardOutPath</key> <string>/tmp/mycommand.out</string> 

Open Console app, in "All Messages" you should see entries when your app fails or succeeds. Like this:

4/28/15 10:43:19.938 AM com.apple.xpc.launchd[1]: (mycommand[18704]) Service exited with abnormal code: 1 

The issue I had was with ProgramArguments takes each item of command as <string> item in the array.

EDIT: In my case, generating a simple wrapper for shell script worked even better. This script sets up basic folder structure to make a shell script into an OS X "app" - https://gist.github.com/mathiasbynens/674099. This might work better for your mysql -u arg1 command.

Answer 2

For me, other solutions so far do not help me. My problem is kinda hard to debug, because the plist file is correct, the script is running fine alone in a terminal. Everything looks fine, but doesn't work.

I checked the log file by executing

tail -f /var/log/system.log 

And then by unloading and loading the service again with the commands:

launchctl unload ~/Library/LaunchAgents/example.plist launchctl load ~/Library/LaunchAgents/example.plist 

I found an error message from the log file:

Program specified by service is not a Mach-O executable file. 

What does it really mean? I didn't google. But, I feel it's because I didn't add #!/bin/bash at the beginning of the shell script. Because I am lazy to add this line sometimes.

After adding the heading, everything works fine.