Reputation: 415
Below is example code:
from subprocess import check_output
list1 = ['df', 'df -h']
for x in list1:
output = check_output([x])
Getting below error for list1 of dh -h value.
File "/usr/lib64/python2.7/subprocess.py", line 568, in check_output
process = Popen(stdout=PIPE, *popenargs, **kwargs)
File "/usr/lib64/python2.7/subprocess.py", line 711, in __init__
errread, errwrite)
File "/usr/lib64/python2.7/subprocess.py", line 1327, in _execute_child
raise child_exception
OSError: [Errno 2] No such file or directory
what is best method to read linux command output's in python2.7
Upvotes: 1
Views: 3816
Reputation: 647
There are a few options with this situation, for ways of passing a cmd
and args
:
# a list broken into individual parts, can be passed with `shell=False
['cmd', 'arg1', 'arg2', ... ]
# a string with just a `cmd`, can be passed with `shell=False`
'cmd`
# a string with a `cmd` and `args`
# can only be passed to subprocess functions with `shell=True`
'cmd arg1 arg2 ...'
Just to follow up on mariis answer. The subprocess docs on python.org have more info on why you may want to pick one of a couple of options.
args
is required for all calls and should be a string, or a sequence of program arguments. Providing a sequence of arguments is generally preferred, as it allows the module to take care of any required escaping and quoting of arguments (e.g. to permit spaces in file names). If passing a single string, eithershell
must beTrue
(see below) or else the string must simply name the program to be executed without specifying any arguments.
(emphesis added)
While adding shell=True
would be OK for this, it's recommended to avoid, as changing 'df -h'
to ['df', '-h']
isn't very difficult, and is a good habit to get into, only using the shell if you really need to. As the docs also add, against a red background no less:
Warning. Executing shell commands that incorporate unsanitized input from an untrusted source makes a program vulnerable to shell injection, a serious security flaw which can result in arbitrary command execution. For this reason, the use of
shell=True
is strongly discouraged in cases where the command string is constructed from external input
Upvotes: 0
Reputation: 1067
I recommend delegator
written by kennethreitz, with his package https://github.com/kennethreitz/delegator.py, you can simply do, and both the API and output is cleaner:
import delegator
cmds = ['df', 'df -h']
for cmd in cmds:
p = delegator.run(cmd)
print(p.out)
Upvotes: 0
Reputation: 5924
You should provide check_output
arguments as a list.
This works:
from subprocess import check_output
list1 = ['df', 'df -h']
for x in list1:
output = check_output(x.split())
Upvotes: 2