MacOS – How to pause Applescript when another process is not responding to system events

applescriptmacosterminalunix

I would like a Applescript to pause while a specific process/script/app is not responding (temporarily or permanently) to system events, and to start-up again when the other process is back. In theory this could be done with a repeat loop provided there is a way to monitor the status of the process. Is there any code that can do this? via Terminal commands? via Applescript? Another possibility: can Applescript determine when the cursor has switched to the beach ball? Other ideas?

Quite simply in applescript terms, this is what I'd like:

repeat while "beach ball is spinning"
end repeat

Best Answer

This may be convoluted but try using try and with timeout to probe for lack of response to an appleEvent. The target app will have to have at least the standard suite dictionary.

try
    with timeout of y seconds
        ## request something simple like set x to name for testing
    end timeout
on error
    ## whatever needs to happen during a stall
end try

Related Solutions

AppleScript: Check if “System Events” has loaded

The System Events process does not start at login, so the delay might be needed for some other reason. System Events also teriminates automatically if it is not used for a few minutes.

It probably won't help, but you could try launching System Events at the start of the script:

launch application "System Events"

You could also try using a launchd agent like this to launch a System Events process at login:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC -//Apple Computer//DTD PLIST 1.0//EN http://www.apple.com/DTDs/PropertyList-1.0.dtd>
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>test</string>
  <key>Program</key>
  <string>/System/Library/CoreServices/System Events.app/Contents/MacOS/System Events</string>
  <key>RunAtLoad</key> <!-- run at login -->
  <true/>
  <key>KeepAlive</key> <!-- run the program again if the previous program terminates -->
  <true/>
</dict>
</plist>

You can normally use something like tell application "System Events" to exists process "Finder" to check if a process exists, but it obviously requires talking to System Events. In this case you might also use a shell script like this:

repeat 100 times
    do shell script "ps -eco comm= | grep -x 'System Events'; exit 0"
    if result is not "" then exit repeat
    delay 0.1
end repeat

ps -e is identical to -ax (include processes from all users and processes without a controlling terminals), -c prints command names instead of absolute paths in OS X, and -o comm= prints only command names without the header row. You can replace the shell command with pgrep -x 'System Events'; exit 0 in 10.8 and later.

Applescript System Events Keystroke broken after 10.9.4

It turns out that the System Events process on my machine was frozen (which I discovered after a node process refused to be killed). Performing a full restart fixed the problem.

Best Answer

Related Solutions

AppleScript: Check if “System Events” has loaded

Applescript System Events Keystroke broken after 10.9.4

Related Question