OS X LaunchAgent should launch an application - macos

Question

i am looking for a way to periodically re-launch an application in OS X. since this application has a GUI i chose the LaunchAgent method to do it. the LaunchAgent will call a shell script, which will quit the application (if running) and then open it again.
so far it works, with the only exception that once my called shell script has ended, the launched GUI application is also quit.
i tried opening the application with trailing "&" and using nohup, but no luck.
this is my LaunchAgent (ignore my stupid StartCalendarInterval settings, they are for debugging only):
<?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>com.mycompany.myapp_relauncher</string>
<key>ProgramArguments</key>
<array>
<string>/Users/xyz/Desktop/myapp_relauncher.sh</string>
</array>
<key>StartCalendarInterval</key>
<dict>
<key>Minute</key>
<integer>21</integer>
<key>Minute</key>
<integer>25</integer>
</dict>
</dict>
</plist>
and this is the called script /Users/xyz/Desktop/myapp_relauncher.sh
#!/bin/bash
function log { echo "myapp: "`date "+%Y%m%d-%H%M%S"`" $1" ; logger -t "myapp" "$1" ; }
# stopping the app if running (code ommitted here)
log "starting application now..."
nohup /Applications/myapp.app/Contents/MacOS/myapp &
log "sleeping a few seconds now..."
sleep 10 # the launched applications stays open
log "done sleeping, quitting."
# script ends, launched application ends too

Answer 1

Add <key>AbandonProcessGroup</key><true/> to your LaunchAgent .plist; without that, when the agent (the script) exits launchd "helpfully" cleans up all leftover subprocesses (technically, anything with the same process group ID), like for example the application.

Answer 2

You want to use disown here. This works without closing the application after the script finishes:
#!/bin/bash
/Applications/Adium.app/Contents/MacOS/Adium &
disown
This is because using & just puts the job into the background. Even though it's in the background it is still a child process of the current script, which is killed when its parent process, the script, finishes. By using disown that relationship is removed and it runs on its own.

Answer 3

You might also just use the open command:
killall myapp; open -jga myapp
open -jg usually opens an application hidden and without raising any windows. If for example TextEdit is open but has no open windows, -jg creates and raises a new default window though. To avoid it, you can test if the application is already open:
<key>ProgramArguments</key>
<array>
<string>bash</string>
<string>-c</string>
<string>pgrep -x TextEdit||open -jga TextEdit</string>
</array>