CODEWITHSUNDEEP
pythonsubprocess
Jeff
Jeff

Reputation: 509

subprocess.check_output failing with error 127

I'm attempting to call an outside program from my python application, but it shows no output and fails with error 127. Executing the command from the command line works fine. (and I am in the correct working directory)

def buildContris (self, startUrl, reportArray):
    urls = []

    for row in reportArray:
        try:
            url = subprocess.check_output(["casperjs", "casper.js", startUrl, row[0]], shell=True)
            print (url)
            urls.append(url)
            break
        except subprocess.CalledProcessError as e:
            print ("Error: " + str(e.returncode) + " Output:" + e.output.decode())          

    return urls

Each loop outputs the following error: (I've also checked e.cmd. It's correct, but long, so I omitted it in this example)

Error: 127 Output:

SOLUTION:

The following code works

app = subprocess.Popen(["./casperjs/bin/casperjs", "casper.js", startUrl, row[0]], stdout=subprocess.PIPE, stderr=subprocess.PIPE, env = {"PATH" : "/usr/local/bin/:/usr/bin"}, universal_newlines=True)
app.wait()
out, errs = app.communicate()

Upvotes: 5

Views: 20794

Answers (4)

t56k
t56k

Reputation: 7011

If you're experiencing this kinda nonsense on macOS: don't use aliases. Lost half a day with that. So, change:

subprocess.check_output(
    "scribus-ng -g -ns -py {0} {1}".format(script_path, id),
    stderr=subprocess.STDOUT,
    shell=True)

to

subprocess.check_output(
    "/Applications/Scribus.app/Contents/MacOS/Scribus -g -ns -py {0} {1}".format(script_path, id),
    stderr=subprocess.STDOUT,
    shell=True)

Upvotes: 1

gdm
gdm

Reputation: 7978

Try to add explicitly the path in this way. If the file to call is in the same path (change __file__ if not):

cwd=os.path.dirname(os.path.realpath(__file__))
a  = subprocess.check_output(["./casper.js", startUrl, row[0]],cwd=cwd,shell=True)

Upvotes: 0

Joe Young
Joe Young

Reputation: 5895

Try adding the full path to casperjs in your subprocess.check_output() call.

Edit: Answeing your 2nd question. My apologies for the formatting as I'm on iPad. I think you should try Popen instead of check_output so that you can specify environment variables:

p = subprocess.Popen(["/path/to/casperjs", "casper.js", startUrl, row[0]], env={"PATH": "/path/to/phantomjs"})
url, err = p.communicate()

Upvotes: 2

jfs
jfs

Reputation: 414845

shell=True changes the interpretation of the first argument (args) in check_output() call, from the docs:

On Unix with shell=True, ... If args is a sequence, the first item specifies the command string, and any additional items will be treated as additional arguments to the shell itself. That is to say, Popen does the equivalent of:

Popen(['/bin/sh', '-c', args[0], args[1], ...])

Exit status 127 might mean that the shell haven't found casperjs program or casperjs itself exited with that code.

To fix the code: drop shell=True and specify the full path to the casperjs program e.g.:

url = check_output(["./casperjs", "casper.js", startUrl, row[0]])

Upvotes: 1

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