Re: Crontab v. Applescript & Command Line
Re: Crontab v. Applescript & Command Line
- Subject: Re: Crontab v. Applescript & Command Line
- From: Gary Beberman <email@hidden>
- Date: Tue, 13 Nov 2001 15:04:15 -0800
If I have it right, these are my options:
1) Find a different timer to trigger this, one which can run under my ID.
2) Always work under root.
3) Find a way to kill the cron processes and restart them under my ID.
4) Try to change the crontab code (a real disaster if I do it).
Right?
Gary
At 10:11 AM -0800 11/13/01, Christopher Nebel wrote:
On Monday, November 12, 2001, at 09:54 PM, Gary Beberman wrote:
I am trying to make a script run automatically in OS X 10.1 using
crontab. Whenever I do, the script starts. And I immediately get
an error dialog telling me:
"Application isn't running"
The strange thing is that the application is running. Even this
simple script trips
tell application "Finder"
open file "OS X:Users:Shared:somefile"
end tell
And the stranger thing is that I can run the script from within
Terminal just fine. If, from the comand line, I call the script
the same way I call it in crontab, it runs perfectly.
What's different in crontab? What can I do about it to get my
Applescripts to run?
You're seeing a security "feature." It has to do with Mach
messages, which form the guts of Apple Events on Mac OS X. For
security reasons, processes in Mach are segregated into "process
groups", and a process in one group is not allowed to send messages
to a process in a different group. Because cron gets launched at
boot time, it's in root's process group, while every application
launched by your login (including the Finder) is in your process
group. Therefore, a script run by cron can't talk to any
application that you launched.
There's something of a bug in AppleScript here, too -- at its level,
it can see the application, so it tells the Apple Event Manager to
send it a message, and you get a surprising error.
It's not clear what the truly correct solution is here -- there are
valid security reasons for keeping the process group restrictions in
place. In the meantime, what can you do? Well, scripting additions
should still work, so you can use those. cron unfortunately makes
sure that only one instance of cron is ever running at once, so you
can't launch your own personal cron, though if you're feeling extra
studly, you could get the source for cron (it is open, after all)
and modify it appropriately.
--Chris Nebel
AppleScript Engineering