[英]Supporting sys.stdin.readlines() as well as command line arguments in python?
I'm working on an application that can be launched directly, or via stdin. 我正在开发可直接或通过stdin启动的应用程序。
Currently if I don't pipe any data to the application an EOF is never received and it hangs waiting for input (such as ctrl+d). 当前,如果我不通过管道将任何数据传输到应用程序,则永远不会收到EOF,并且EOF会挂起以等待输入(例如ctrl + d)。 That code looks like: 该代码如下所示:
while True:
line = sys.stdin.readline()
print("DEBUG: %s" % line)
if not line:
break
I've also tried: 我也尝试过:
for line in sys.stdin:
print("DEBUG (stdin): %s" % line)
return
However in both cases an EOF isn't received if the program is launched directly so it hangs waiting for it. 但是,在这两种情况下,如果直接启动程序,它都将挂起等待,但不会收到EOF。
I've seen some unix applications pass a single -
command line flag in cases where stdin input is expected but I'm wondering if there's a better workaround then this? 我已经看到了一些UNIX应用程序通过一个单一的-
的情况下命令行标志,在标准输入输入预期,但我不知道是否有更好的解决方法,然后呢? I'd rather the user be able to use the application interchangeably without remembering to add a -
flag. 我希望用户可以互换使用该应用程序,而无需记住添加-
标志。
The best you can do is to check whether standard input is a TTY, and, if so, not read it: 最好的办法是检查标准输入是否为TTY,如果是,则不要阅读它:
$ cat test.py
import sys
for a in sys.argv[1:]:
print("Command line arg:", a)
if not sys.stdin.isatty():
for line in sys.stdin:
print("stdin:", line, end="")
$ python3 test.py a b c
Command line arg: a
Command line arg: b
Command line arg: c
$ { echo 1; echo 2; } | python3 test.py a b c
Command line arg: a
Command line arg: b
Command line arg: c
stdin: 1
stdin: 2
$ python3 test.py a b c < test.py
Command line arg: a
Command line arg: b
Command line arg: c
stdin: import os, sys
stdin:
stdin: for a in sys.argv[1:]:
stdin: print("Command line arg:", a)
stdin:
stdin: if not sys.stdin.isatty():
stdin: for line in sys.stdin:
stdin: print("stdin:", line, end="")
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