How AppleScript can get STDIN inside the code? - macos

Question

Google suggests
echo "input" | osascript filename.scpt
with filename.scpt
set stdin to do shell script "cat"
display dialog stdin
However, I could get only blank dialog: it has no text. How can I get stdin from AppleScript at the version?
My OS version is OSX 10.8 Mountain Lion.

Answer 1

Sorry, not enough reputation to comment on answers, but I think there's something important worth pointing out here...
The solution in #regulus6633's answer is not the same as piping data into osascript. It's simply stuffing the entire pipe contents (in this case, echo output) into a variable and passing that to osascript as a commandline argument.
This solution may not work as expected depending on what's in your pipe (maybe your shell also plays a part?)... for example, if there are null (\0) characters in there:
$ var=$(echo -en 'ABC\0DEF')
Now you might think var contains the strings "ABC" and "DEF" delimited by a null character, but it doesn't. The null character is gone:
$ echo -n "$var" | wc -c
6
However, using #phs's answer (a true pipe), you get your zero:
$ echo -en 'ABC\0DEF' | osascript 3<&0 <<EOF
> on run argv
> return length of (do shell script "cat 0<&3")
> end run
>EOF
7
But that's just using zeros. Try passing some random binary data into osascript as a commandline argument:
$ var=$(head -c8 /dev/random)
$ osascript - "$var" <<EOF
> on run argv
> return length of (item 1 of argv)
> end run
>EOF
execution error: Can’t make some data into the expected type. (-1700)
Once again, #phs's answer will handle this fine:
$ head -c8 /dev/random | osascript 3<&0 <<EOF
> on run argv
> return length of (do shell script "cat 0<&3")
> end run
>EOF
8

Answer 2

According to this thread, as of 10.8 AppleScript now aggressively closes standard in. By sliding it out of the way to an unused file descriptor, it can be saved. Here's an example of doing that in bash.
Here we get at it again with a cat subprocess reading from the magic fd.
echo world | osascript 3<&0 <<'APPLESCRIPT'
on run argv
set stdin to do shell script "cat 0<&3"
return "hello, " & stdin
end run
APPLESCRIPT
Will give you:
hello, world

Answer 3

I know that "set stdin to do shell script "cat"" used to work. I can't get it to work in 10.8 though and I'm not sure when it stopped working. Anyway, you basically need to get the echo command output into a variable which can then be used as an argument in the osascript command. Your applescript needs to handle arguments too (on run argv). And finally, when you use osascript you must tell an application to "display dialog" otherwise it will error.
So with all that said here's a simple applescript which handles arguments. Make this the code of filename.scpt.
on run argv
repeat with i from 1 to count of argv
tell application "Finder"
activate
display dialog (item i of argv)
end tell
end repeat
end run
Here's the shell command to run...
var=$(echo "sending some text to an applescript"); osascript ~/Desktop/filename.scpt "$var"
I hope that helps. Good luck.

Answer 4

Late to this, but the original AppleScript seems to try to do something not allowed with osascript.
If in the original filename.scpt this line:
display dialog stdin
Is changed to:
tell application "System Events" to display dialog stdin
Then passing a value via stdin (as opposed to command line arguments) definitely still works in 10.7.5 Lion, maybe 10.8 Mountain Lion too.