python中是否有办法判断变量是否为系统命令

Question

我正在用python创建一个shell模拟器，但是我想必须将用户输入保存到名为x的变量中（如果它是系统命令）

我试图列出每个命令的清单，但这太浪费时间了

0                                              blah blah card# visa 561100004331****
1                              blah blah card# visa 561100004331**** with text after
2                                                                   561100004331****
3    visa: 561100004331**** and random number > 16 digits: 0011237324763246723487243

Answer 1

如果您已经有了命令列表，则可以执行以下操作：

>>> from subprocess import Popen, PIPE
>>> 
>>> 
>>> def get_stderr(cmd):
...     return Popen(cmd, shell=True, stderr=PIPE).communicate()[1]
... 
>>> 
>>> for c in ['garbage_cmd1', 'grep', 'which', 'garbage_cmd2']:
...     if 'not found' in get_stderr(c).decode():
...         print('%s is not valid' % c)
...     else:
...         print('%s is valid' % c)
... 
garbage_cmd1 is not valid
grep is valid
which is valid
garbage_cmd2 is not valid

如果您使用的是Linux计算机，则还可以运行compgen -c >> cmds.txt