Call Perl script from Python

Question

I've got a Perl script that I want to invoke from a Python script. I've been looking all over, and haven't been successful. I'm basically trying to call the Perl script sending 1 variable to it, but don't need the output of the Perl script, as it is a self contained program.

What I've come up with so far is:

var = "/some/file/path/"
pipe = subprocess.Popen(["./uireplace.pl", var], stdin=subprocess.PIPE)
pipe.stdin.write(var)
pipe.stdin.close()

Only just started Python programming, so I'm sure the above is total nonsense. Any help would be much appreciated.

mouad · Accepted Answer · 2011-01-13 16:01:49Z

17

Just do:

var = "/some/file/path/"
pipe = subprocess.Popen(["perl", "uireplace.pl", var])

answered Jan 13, 2011 at 16:01

mouad

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5 Comments

user225312 Over a year ago

Just a note: since the OP says he doesn't want to get the output, Popen is not required. Using subprocess.call or subprocess.check_call is better.

mouad Over a year ago

@sukhbir: i think when the OP say that he don't need the output, i can also "assume" that he also don't want to wait until the perl script finish which what subprocess.call or subprocess.check_call does :)

pyCthon Over a year ago

so using this if the perl script were to run in terminal and i want to rerun it everytime the perl script crashed, and would have to use an if pipe = error message than rerun the perl code or something like that?

mouad Over a year ago

@pyCthon: Sorry but i didn't understand very well your question, what i understood is that you're running a Perl script using the code above and you want to make sure that if the Perl script crash, it should be re-spawn, right ?

mouad Over a year ago

@pyCthon; Well i am not sure about the context where you want to do this, but one way that i can think about is to execute Popen.poll (docs.python.org/2/library/subprocess.html#subprocess.Popen.poll) at a fix interval to check if the process is alive or not, so you can re-spawn it when it's crash i.e. Popen.pool() != 0, you can run this mechanism in a Thread for example, other ways will involve using something like upstart.ubuntu.com or supervisord.org .

Ken Kinder · Accepted Answer · 2011-01-13 16:06:07Z

16

If you just want to open a pipe to a perl interpreter, you're on the right track. The only thing I think you're missing is that the perl script itself is not an executable. So you need to do this:

var = "/some/file/path/"
pipe = subprocess.Popen(["perl", "./uireplace.pl", var], stdin=subprocess.PIPE)
pipe.stdin.write(var)
pipe.stdin.close()

answered Jan 13, 2011 at 16:06

Ken Kinder

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2 Comments

mouad Over a year ago

the ./ part in the script call is useless and i can't see the use of the two last line, and this two last line can lead to bugs !!

bimlesh sharma Over a year ago

If you are providing absolute path and perl executable then ./ is not in use.

bedwyr · Accepted Answer · 2011-01-13 16:01:40Z

3

You could try the subprocess.call() method. It won't return output from the command you're invoking, but rather the return code to indicate if the execution was successful.

var = "/some/file/path"
retcode = subprocess.call(["./uireplace.pl", var])
if retcode == 0:
    print("Passed!")
else:
    print("Failed!")

Make sure you're Perl script is executable. Otherwise, you can include the Perl interpreter in your command (something like this):

subprocess.call(["/usr/bin/perl", "./uireplace.pl", var])

answered Jan 13, 2011 at 16:01

bedwyr

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Comments

Sven Marnach · Accepted Answer · 2011-01-13 16:01:13Z

2

Would you like to pass var as a parameter, on stdin or both? To pass it as a parameter, use

subprocess.call(["./uireplace.pl", var])

To pipe it to stdin, use

pipe = subprocess.Popen("./uireplace.pl", stdin=subprocess.PIPE)
pipe.communicate(var)

Both code snippets require uireplace.pl to be executable. If it is not, you can use

pipe = subprocess.Popen(["perl", "./uireplace.pl"], stdin=subprocess.PIPE)
pipe.communicate(var)

answered Jan 13, 2011 at 16:01

Sven Marnach

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Comments

Donovan · Accepted Answer · 2011-01-13 15:59:15Z

0

I Hope this can help you. Do not know how to do that otherwise.

answered Jan 13, 2011 at 15:59

Donovan

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1 Comment

Tagar Over a year ago

thank you for the reference... it was created and supported by activestate.. they seems dropped it?

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