子进程签出OSError：[Errno 2]没有这样的文件或目录

Question

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

Answer 1

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())

Answer 2

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)

Answer 3

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 marii s 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 (eg to permit spaces in file names) . If passing a single string, either shell must be True (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