How do you make a program run when any user logs in?

Question

I have an application which will need to run when any users logs in.
Such that Joe downloads and installs the application, logs out, then Sally logs in and the application runs for Sally.
Does anyone know how to do this?

Answer 1

Hey Steve, thanks for that link. It seems to be what
I am looking for. What is the meaning of the
~/Library vs /Library ? They are definitely
different folders.
Yes, they are definitely different folders. The "~" character represents the current users home folder, so "~/Library" represents the Library folder that's located inside a users home folder. Anything placed in there will only affect the one user whose home folder you've accessed.
The "/Library" folder is the Library folder that exists at to root of the boot volume. Things placed in this Library folder will affect all users of the system. Basically it's sort of a "global" Library.
Also, from a script, how do I add an item to execute
for that kind of PList?
That could be tricky based on the structure of that particular plist file. I haven't really looked at it closely but one place you could start is to read the "man" page for the "defaults" command... enter "man defaults" in Terminal. The "defaults" command allows you to read/write plist files, but defaults is not very good at accessing deeply nested plist items.
Related to that, how do I tell if the logging item
for my App is already there? I do not want to keep
adding to the list if it is there. If someone
deletes my app and then reinstalls it, I do not want
it to run twice, three times, etc..
Again, you could possibly read the plist using the defaults command and determine whether your item was already present or not.
Do you know of the one in the ~/Library path, what
user it execute as? Since it is all users, it
probably is root or something like that.
No, the one in ~/Library is in each individual user home folder. It will execute with the current user's privileges. This is where Login Items normally go when you go through the GUI... "Sys.Prefs -> Accounts -> Login Items" and add a login item for one user.
Even items placed in /Library, which should execute for all users, will execute with the current user's privileges.
In the near
future we might need root privileges, so I might need
a program to startup for all users as root instead of
the user.
Is your app, that needs to run at login time, a GUI application or is it a faceless shell script (or something similar). Your original post gave me the impression that you needed to launch a GUI application. However, if it's a shell script then you probably want to look at doing a LoginHook instead of using the Login Items procedure at the web page I posted earlier. I believe a LoginHook will also give you the ability to run the script as root.
Check out this link at the ADC website.
or
Take a look at this information and this utility at Mike Bombich's website.
Steve