没有这样的文件或目录错误与Python中的subprocess.call

Question

一般来说，我想使用Bash从命令行而不是Python读取，所以我有选项卡完成功能。我想尽可能以最简单的方式做到这一点。但是，我无法使下面的代码正常工作，我想了解是什么导致了这个问题。

的Python脚本：

from subprocess import call 
call(['read', '-ep', 'Path:', 'temporaryPath']) 
print temporaryPath 

错误回溯：

Traceback (most recent call last): 
    File "tmp.py", line 2, in <module> 
    call(['read', '-ep', 'Path:', 'temporaryPath']) 
    File "/usr/lib64/python2.6/subprocess.py", line 478, in call 
    p = Popen(*popenargs, **kwargs) 
    File "/usr/lib64/python2.6/subprocess.py", line 642, in __init__ 
    errread, errwrite) 
    File "/usr/lib64/python2.6/subprocess.py", line 1238, in _execute_child 
    raise child_exception 
OSError: [Errno 2] No such file or directory 

Answer 1

你试图调用read这是一个shell内建：

$ type read 
read is a shell builtin 

和内置有这种特殊的外壳没有同等课程：

$ which read 
$ 

所以Python将无法找到它在你的PATH环境变量，根据strace：

[pid 17266] execve("/usr/local/bin/read", ["read", "-ep", "Path:", "temporaryPath"], [/* 70 vars */]) = -1 ENOENT (No such file or directory) 
[pid 17266] execve("/usr/bin/read", ["read", "-ep", "Path:", "temporaryPath"], [/* 70 vars */]) = -1 ENOENT (No such file or directory) 
[pid 17266] execve("/bin/read", ["read", "-ep", "Path:", "temporaryPath"], [/* 70 vars */]) = -1 ENOENT (No such file or directory) 
[pid 17266] execve("/usr/local/games/read", ["read", "-ep", "Path:", "temporaryPath"], [/* 70 vars */]) = -1 ENOENT (No such file or directory) 
[pid 17266] execve("/usr/games/read", ["read", "-ep", "Path:", "temporaryPath"], [/* 70 vars */]) = -1 ENOENT (No such file or directory) 
[…] 
[pid 17266] write(4, "OSError:", 8 <unfinished ...> 

但是，如果你明确要求Python的使用shell来执行你的命令，外壳本身将能够运行其内置read：

$ python3 
Python 3.5.3 (default, Jan 19 2017, 14:11:04) 
[GCC 6.3.0 20170118] on linux 
Type "help", "copyright", "credits" or "license" for more information. 
>>> import subprocess 
>>> subprocess.call('read', shell=True) 
/bin/sh: 1: read: arg count 
2 
>>> subprocess.call('read foo', shell=True) 
hello world 
0 

您现在有一个新的问题：内置read被存储读取值作为一个shell变量的外壳，这将diseapear无线在呼叫subprocess.call之后，外壳正在死亡。

哦，在read shell内建中，你也没有完成。如果您想交互式地向用户提问，或者如果不需要交互，只需使用argparse解析用户作为命令行参数提供的内容即可，您应该只使用input，这样用户在键入命令行参数时就会有一些shell完成参数通常不在标志上，因为用户shell不知道它们，但是在路径上。