Why does the curl command fail when run through applescript but work fine when I run directly in a terminal

The approach given here looks a little simpler—maybe it would work for you?

If you don't want to remember to type "quit" instead of "exit", and you're using bash, just add the following to your .bashrc or other shell startup script:

trap '/usr/bin/osascript -e "tell application \"terminal\" to quit"' 0

What's it do? When the shell receives signal 0 (zero), that is, told to exit, it will execute this command as the last thing it does. This allows your shell, etc, to exit gracefully, and asking Terminal.app to exit via applescript makes sure it does the same. In other words, type 'exit', and your shell exits, then Terminal quits, all cleanly and the way nature intended.

The full thread can be found here.

Perhaps you can write a loop that keeps track of whether or not the script has succeeded and keeps trying until it has (or some cutoff amount of time has passed). If indeed the problem is that system events is not fully started up, then the loop could ask system events if the application system events is running. Here's a simple function you could use:

on appIsRunning(appName)
    tell application "System Events" to (name of processes) contains appName
end appIsRunning

Just to be sure it has started up fully, you could implement your delay after the loop.

Here's what the loop function would look like:

on startApp(appName)
    set IsRunning to false
    set tries to 20
    repeat until (IsRunning is true or tries is 0)
        set IsRunning to appIsRunning(appName)
        set tries to (tries - 1)
        delay 0.1
    end repeat
end startApp

Or, maybe you have some other way of determining the successful running of the script… is there some state you can check to determine success? If so, you could loop until that condition is met instead of on whether System Events has started up.

Another thing is, I don't know if system events has to "register" with applescript before an applescript fires off in order for it to work. If it does, then you might try this: you can make a separate helper script that starts up system events and then runs your script like this:

startApp("System Events")
set myApp to "/Users/whatever/myScriptAsApp.app"
do shell script "open " & quoted form of POSIX path of myApp & " 2>&1 &"

Let me know how it goes. I frequently have the same problem as you with a couple of my scripts. I just haven't tried this yet.

Good luck, Rob