Can't do shell script with a repeat with i from 1 to n loop

Question

This works (prints, for example, “3 arguments”):

to run argv
 do shell script "echo " & (count argv) & " arguments"
end run

This doesn't (prints only “Argument 3: three”, and not the previous two arguments):

to run argv
 do shell script "echo " & (count argv) & " arguments"

 repeat with i from 1 to (count argv)
  do shell script "echo 'Argument " & i & ": " & (item i of argv) & "'"
 end repeat
end run

In both cases, I'm running the script using osascript on Mac OS X 10.5.5. Example invocation:

osascript 'Script that takes arguments.applescript' Test argument three

I'm not redirecting the output, so I know that the script is not throwing an error.

If I add a display dialog statement above the do shell script, it throws a “no user interaction allowed” error, so I know that it is executing the loop body.

What am I doing wrong? What is it about this loop that causes osascript to not print anything?

Answer 1

Your problem appears to be unrelated to the loop, or the use of argv, for that matter. Here's a much simpler test case where only the last do shell script actually returns a result:

do shell script "echo foo"
delay 2
do shell script "echo bar"

In addition, the following slight change will produce expected results:

to run argv
    do shell script "echo " & (count argv) & " arguments > /test.txt"

    repeat with i from 1 to (count argv)
     do shell script "echo 'Argument " & i & ": " & (item i of argv) & "' >> /test.txt"
    end repeat
end run

test.txt will contain four lines, like so:

3 arguments
Argument 1: foo
Argument 2: bar
Argument 3: baz

This workaround fails:

to run argv
    do shell script "echo " & (count argv) & " arguments > /tmp/foo.txt"

    repeat with i from 1 to (count argv)
     do shell script "echo 'Argument " & i & ": " & (item i of argv) & "' >> /tmp/foo.txt"
    end repeat

    do shell script "cat /tmp/foo.txt"
    do shell script "rm /tmp/foo.txt"
end run

Even now, only the last line is returned. This may be related to the following question of TN2065:

Q: My script will produce output over a long time. How do I read the results as they come in?

A: Again, the short answer is that you don’t — do shell script will not return until the command is done. In Unix terms, it cannot be used to create a pipe. What you can do, however, is to put the command into the background (see the next question), send its output to a file, and then read the file as it fills up.

Alas, I don't have enough AppleScript-fu to know how to have AppleScript itself read multiple lines, which I suspect would work.

Answer 2

Try this to avoid having to use the temporary file.

to run argv
        set accumulator to do shell script "echo " & (count argv) & " arguments" altering line endings false
        repeat with i from 1 to (count argv)
                set ln to do shell script "echo 'Argument " & i & ": " & (item i of argv) & "'" altering line endings false
                set accumulator to accumulator & ln
        end repeat
        return accumulator
end run