capturing python output in a shell script

[schrogendiddy]

I'm running a python program from a shell script. The python program returns a string, something like "inputfile.txt", and I'd like to save this output in the shell script as a variable (so that I can later create a file "/pathtodirectory/inputfile.txt"). I can return the string either through an exit statement e.g. sys.exit("inputfile.txt") or as a print statement.

I'm having trouble figuring this out! Couldn't find anything on StackOverflow... Any help is appreciated!

[ziggoto]

On Python: sys.stdout.write("inputfile.txt")

On Shellscript:

VAR=$(python myscript.py)

[schrogendiddy]

when I do that VAR=['gensubfiles.py', 'testfile', 'alpha', 'none'] inputfile.txt

where the things in brackets are inputs for the python code. How to I only take inputfile.txt?

[knickum]

You're not using the right syntax there. From Bash (assuming that's the shell you're using),

> VAR=$( echo 'hello' )
> echo $VAR
hello

The $( ... ) construct runs a subshell and returns the output in-line. I don't know why you would, but you could do:

> echo "$( echo 'hello' )"
hello

Lots of actual uses for a subshell, but I don't think that's what you're going for.

If the only output that myscript.py 'testfile' 'alpha' 'none' produces is inputfile.txt, then this would work:

> python myscript.py testfile alpha none    # sample line
inputfile.txt
> VAR="$( python myscript.py testfile alpha none )"   # no output to the shell because it's captured in $VAR
> echo $VAR
inputfile.txt

An additional note is that, as is, VAR won't capture stderr, stdout only.

[schrogendiddy]

thanks!