python 2.7 getting below error while running the script

Question

I have the following code in Python 2.7 and am receiving the following error.

import os,subprocess,re
f = open("/var/tmp/disks_out", "w")
proc = subprocess.Popen(
    ["df", "-h"],
    stdout=subprocess.PIPE,
    stderr=subprocess.PIPE
)
out, err = proc.communicate()
for line in out:
    f.write(line)
f.close()
f1 = open("/var/tmp/disks_out","r")
disks = []
for line in f1:
    m = re.search(r"(c\dt\d.{19})",line)
    if m:
        disk = m.group[1]
        disks.append(disk)
print(disks)

Error:

disk = m.group[1]
TypeError: 'builtin_function_or_method' object is unsubscriptable

Does anyone know why this is happening?

Answer 1

What you are doing is -

m.group[1]

But rather it should be -

m.group(1)

Look here

Example from docs -

>>> m = re.match(r"(\w+) (\w+)", "Isaac Newton, physicist")
>>> m.group(0)       # The entire match
'Isaac Newton'
>>> m.group(1)       # The first parenthesized subgroup.
'Isaac'
>>> m.group(2)       # The second parenthesized subgroup.
'Newton'
>>> m.group(1, 2)    # Multiple arguments give us a tuple.
('Isaac', 'Newton')

What you are doing instead is-

disk=m.group[1]
# Trying to slice a builtin method, in this case, you are trying to slice group()
# and hence
TypeError: 'builtin_function_or_method' object is unsubscriptable

Square brackets [] are the subscript operator. If you try to apply the subscript operator to an object that does not support it, you get the error.