How to fix/get awk command called by subprocess working in script (works in python shell)?

Question

I'm trying to get the following command to be called from a python script and to get the output of the command: awk -F':' '$1 == "VideoEdge" {print $2, $3, $8}' /etc/shadow

I've got the function working using subprocess.check_output and .Popen in a python shell but when called from a script it doesn't work and causes an exception of which has no apparent output or message.

How can I get this command working from a script?

I've tried using check_output, Popen and shlex to help with possible issues I thought were causing the issue. Code works fine in a shell.

temp = "User"
cmd = "awk -F':' '$1 == \"" + temp + "\" {print $2, $3, $8}' /etc/shadow"
cmdOutput = subprocess.check_output(shlex.split(cmd))
print cmdOutput

temp = "User"
cmd = "awk -F':' '$1 == \"" + temp + "\" {print $2, $3, $8}' /etc/shadow"
cmdOutput = subprocess.Popen(cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE)
print cmdOutput.communicate()[0]

That first block runs fine.On the second ,do subprocess.Popen(shlex(cmd), stdin=PIPE, stdout=PIPE, stderr=PIPE) — han solo
– han solo, Commented Mar 27, 2019 at 13:55

han solo · Accepted Answer · 2019-03-27 13:58:40Z

1

I'd just do. [Just for user consideration, (it will be cryptic, in the comments)]

user = "someuser"
with open('/etc/shadow') as f:
    for line in f:
        if line.startswith(user):
            data = line.split(':')
            break
print(data)

answered Mar 27, 2019 at 13:58

han solo

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Artem Trunov · Accepted Answer · 2019-03-27 14:04:26Z

1

Make the same shlex.split(cmd) and it will work:

cmdOutput = subprocess.Popen(shlex.split(cmd), stdin=PIPE, stdout=PIPE, stderr=PIPE)

answered Mar 27, 2019 at 14:04

Artem Trunov

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2 Comments

AceVenturos Over a year ago

Thanks, it works in the python shell but not the script, does subprocess wait for the command to finish? cmdoutput.communicate()[0] is returning an empty value in the script but work as expected in a shell

Artem Trunov Over a year ago

It did work in the script for me, once I wrapped cmd in shlex in the the Popen() invocation.

AceVenturos · Accepted Answer · 2019-03-28 17:31:17Z

0

I had a permission issue with the file i was performing the command. bangs head against desk

answered Mar 28, 2019 at 17:31

AceVenturos

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