我如何在Python中命名一个外部命令,就好像我把它写在一个<unk>或命令中?


当前回答

import os
cmd = 'ls -al'
os.system(cmd)

如果你想返回命令的结果,你可以使用os.popen. 但是,这是由于版本 2.6 有利于子过程模块,其他答案已经覆盖得很好。

其他回答

2015 年更新: Python 3.5 添加了 subprocess.run 比 subprocess.Popen 更容易使用。

>>> subprocess.run(["ls", "-l"])  # doesn't capture output
CompletedProcess(args=['ls', '-l'], returncode=0)

>>> subprocess.run("exit 1", shell=True, check=True)
Traceback (most recent call last):
  ...
subprocess.CalledProcessError: Command 'exit 1' returned non-zero exit status 1

>>> subprocess.run(["ls", "-l", "/dev/null"], capture_output=True)
CompletedProcess(args=['ls', '-l', '/dev/null'], returncode=0,
stdout=b'crw-rw-rw- 1 root root 1, 3 Jan 23 16:23 /dev/null\n', stderr=b'')

使用副过程。

或者一个非常简单的命令:

import os
os.system('cat testfile')

我写了一封信来处理错误,并重新引导输出和其他东西。

import shlex
import psutil
import subprocess

def call_cmd(cmd, stdout=sys.stdout, quiet=False, shell=False, raise_exceptions=True, use_shlex=True, timeout=None):
    """Exec command by command line like 'ln -ls "/var/log"'
    """
    if not quiet:
        print("Run %s", str(cmd))
    if use_shlex and isinstance(cmd, (str, unicode)):
        cmd = shlex.split(cmd)
    if timeout is None:
        process = subprocess.Popen(cmd, stdout=stdout, stderr=sys.stderr, shell=shell)
        retcode = process.wait()
    else:
        process = subprocess.Popen(cmd, stdout=stdout, stderr=sys.stderr, shell=shell)
        p = psutil.Process(process.pid)
        finish, alive = psutil.wait_procs([p], timeout)
        if len(alive) > 0:
            ps = p.children()
            ps.insert(0, p)
            print('waiting for timeout again due to child process check')
            finish, alive = psutil.wait_procs(ps, 0)
        if len(alive) > 0:
            print('process {} will be killed'.format([p.pid for p in alive]))
            for p in alive:
                p.kill()
            if raise_exceptions:
                print('External program timeout at {} {}'.format(timeout, cmd))
                raise CalledProcessTimeout(1, cmd)
        retcode = process.wait()
    if retcode and raise_exceptions:
        print("External program failed %s", str(cmd))
        raise subprocess.CalledProcessError(retcode, cmd)

你可以这样称之为:

cmd = 'ln -ls "/var/log"'
stdout = 'out.txt'
call_cmd(cmd, stdout)

下面是一个Python脚本,它将在Ubuntu上运行命令,同时在实时显示日志:

command = 'your command here'    
process = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    while True:
        output = process.stdout.readline().decode()
        if output == '' and process.poll() is not None:
            break
        if output:
            print(output.strip())
    rc = process.poll()
    if rc == 0:
        print("Command succeeded.")
       
    else:
        print("Command failed.")

使用:

import subprocess

p = subprocess.Popen("df -h", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()[0]
print p.split("\n")

它提供良好的产量,更容易与:

['Filesystem      Size  Used Avail Use% Mounted on',
 '/dev/sda6        32G   21G   11G  67% /',
 'none            4.0K     0  4.0K   0% /sys/fs/cgroup',
 'udev            1.9G  4.0K  1.9G   1% /dev',
 'tmpfs           387M  1.4M  386M   1% /run',
 'none            5.0M     0  5.0M   0% /run/lock',
 'none            1.9G   58M  1.9G   3% /run/shm',
 'none            100M   32K  100M   1% /run/user',
 '/dev/sda5       340G  222G  100G  69% /home',
 '']