Linux:传送到Python(ncurses)脚本，stdin和termios [英] Linux: Pipe into Python (ncurses) script, stdin and termios
问题描述
显然，这几乎是"错误的管道文件描述符的副本在python中从stdin读取时-堆栈溢出；但是，我认为这种情况稍微复杂一些(，并且不是Windows特定的，因为该线程的结论是).
Apparently this is almost a duplicate of "Bad pipe filedescriptor when reading from stdin in python - Stack Overflow"; however, I believe this case is slightly more complicated (and it is not Windows specific, as the conclusion of that thread was).
我目前正在尝试使用Python编写一个简单的脚本:我想通过脚本参数为脚本提供输入.或通过'pipe'-将字符串输入此脚本-并让脚本使用curses终端界面显示此输入字符串.
I'm currently trying to experiment with a simple script in Python: I'd like to supply input to the script - either through command line arguments; or by 'pipe'-ing a string to this script - and have the script show this input string using a curses terminal interface.
下面给出了完整的脚本，这里称为testcurses.py.问题在于，每当我尝试实际的管道传输时，似乎都会弄乱标准输入，而curses窗口将永远不会显示.这是终端输出:
The full script, here called testcurses.py, is given below. The problem is that whenever I try the actual piping, that seems to mess up stdin, and the curses window never shows. Here is a terminal output:
## CASE 1: THROUGH COMMAND LINE ARGUMENT (arg being stdin):
##
$ ./testcurses.py -
['-'] 1
stdout/stdin (obj): <open file '<stdout>', mode 'w' at 0xb77dc078> <open file '<stdin>', mode 'r' at 0xb77dc020>
stdout/stdin (fn): 1 0
env(TERM): xterm xterm
stdin_termios_attr [27906, 5, 1215, 35387, 15, 15, ['\x03', ... '\x00']]
stdout_termios_attr [27906, 5, 1215, 35387, 15, 15, ['\x03', ... '\x00']]
opening -
obj <open file '<stdin>', mode 'r' at 0xb77dc020>
TYPING blabla HERE
wr TYPING blabla HERE
at end
before curses TYPING blabla HERE
#
# AT THIS POINT:
# in this case, curses window is shown, with the text 'TYPING blabla HERE'
# ################
## CASE 2: THROUGH PIPE
##
## NOTE I get the same output, even if I try syntax as in SO1057638, like:
## python -c "print 'TYPING blabla HERE'" | python testcurses.py -
##
$ echo "TYPING blabla HERE" | ./testcurses.py -
['-'] 1
stdout/stdin (obj): <open file '<stdout>', mode 'w' at 0xb774a078> <open file '<stdin>', mode 'r' at 0xb774a020>
stdout/stdin (fn): 1 0
env(TERM): xterm xterm
stdin_termios_attr <class 'termios.error'>::(22, 'Invalid argument')
stdout_termios_attr [27906, 5, 1215, 35387, 15, 15, ['\x03', '\x1c', '\x7f', '\x15', '\x04', '\x00', '\x01', '\xff', '\x11', '\x13', '\x1a', '\xff', '\x12', '\x0f', '\x17', '\x16', '\xff', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00']]
opening -
obj <open file '<stdin>', mode 'r' at 0xb774a020>
wr TYPING blabla HERE
at end
before curses TYPING blabla HERE
#
# AT THIS POINT:
# script simply exits, nothing is shown
# ################
据我所知，问题是:-每当我们将字符串通过管道传递到Python脚本时，Python脚本都会丢失对 terminal 的引用，为stdin，并注意到替换为stdin不再是termios结构-并且由于stdin不再是终端，所以curses.initscr()会立即退出而不呈现任何内容.
As far as I can see, the issue is: - whenever we pipe strings into the Python script, the Python script loses the reference to the terminal as stdin, and notices that the replaced stdin is not a termios structure anymore - and since stdin is no longer a terminal, curses.initscr() exits immediately without rendering anything.
因此，我的问题是-简而言之:我能以某种方式实现语法echo "blabla" | ./testcurses.py -最终显示curses中的管道字符串吗?更具体地说:是否可以从Python脚本中检索对呼叫终端的stdin的引用，即使该脚本被管道传输"到了?
So, my question is - in brief: can I somehow achieve, that the syntax echo "blabla" | ./testcurses.py - ends up showing the piped string in curses? More specifically: is it possible to retrieve a reference to the calling terminal's stdin from a Python script, even if this script is being "piped" to?
预先感谢任何指针，
干杯！
PS:testcurses.py脚本:
#!/usr/bin/env python
# http://www.tuxradar.com/content/code-project-build-ncurses-ui-python
# http://diveintopython.net/scripts_and_streams/stdin_stdout_stderr.html
# http://bytes.com/topic/python/answers/42283-curses-disable-readline-replace-stdin
#
# NOTE: press 'q' to exit curses - Ctrl-C will screw up yer terminal
# ./testcurses.py "blabla" # works fine (curseswin shows)
# ./testcurses.py - # works fine, (type, enter, curseswins shows):
# echo "blabla" | ./testcurses.py "sdsd" # fails to raise curses window
#
# NOTE: when without pipe: termios.tcgetattr(sys.__stdin__.fileno()): [27906, 5, 1215, 35387, 15, 15, ['\x03',
# NOTE: when with pipe | : termios.tcgetattr(sys.__stdin__.fileno()): termios.error: (22, 'Invalid argument')
import curses
import sys
import os
import atexit
import termios
def openAnything(source):
"""URI, filename, or string --> stream
http://diveintopython.net/xml_processing/index.html#kgp.divein
This function lets you define parsers that take any input source
(URL, pathname to local or network file, or actual data as a string)
and deal with it in a uniform manner. Returned object is guaranteed
to have all the basic stdio read methods (read, readline, readlines).
Just .close() the object when you're done with it.
"""
if hasattr(source, "read"):
return source
if source == '-':
import sys
return sys.stdin
# try to open with urllib (if source is http, ftp, or file URL)
import urllib
try:
return urllib.urlopen(source)
except (IOError, OSError):
pass
# try to open with native open function (if source is pathname)
try:
return open(source)
except (IOError, OSError):
pass
# treat source as string
import StringIO
return StringIO.StringIO(str(source))
def main(argv):
print argv, len(argv)
print "stdout/stdin (obj):", sys.__stdout__, sys.__stdin__
print "stdout/stdin (fn):", sys.__stdout__.fileno(), sys.__stdin__.fileno()
print "env(TERM):", os.environ.get('TERM'), os.environ.get("TERM", "unknown")
stdin_term_attr = 0
stdout_term_attr = 0
try:
stdin_term_attr = termios.tcgetattr(sys.__stdin__.fileno())
except:
stdin_term_attr = "%s::%s" % (sys.exc_info()[0], sys.exc_info()[1])
try:
stdout_term_attr = termios.tcgetattr(sys.__stdout__.fileno())
except:
stdout_term_attr = `sys.exc_info()[0]` + "::" + `sys.exc_info()[1]`
print "stdin_termios_attr", stdin_term_attr
print "stdout_termios_attr", stdout_term_attr
fname = ""
if len(argv):
fname = argv[0]
writetxt = "Python curses in action!"
if fname != "":
print "opening", fname
fobj = openAnything(fname)
print "obj", fobj
writetxt = fobj.readline(100) # max 100 chars read
print "wr", writetxt
fobj.close()
print "at end"
sys.stderr.write("before ")
print "curses", writetxt
try:
myscreen = curses.initscr()
#~ atexit.register(curses.endwin)
except:
print "Unexpected error:", sys.exc_info()[0]
sys.stderr.write("after initscr") # this won't show, even if curseswin runs fine
myscreen.border(0)
myscreen.addstr(12, 25, writetxt)
myscreen.refresh()
myscreen.getch()
#~ curses.endwin()
atexit.register(curses.endwin)
sys.stderr.write("after end") # this won't show, even if curseswin runs fine
# run the main function - with arguments passed to script:
if __name__ == "__main__":
main(sys.argv[1:])
sys.stderr.write("after main1") # these won't show either,
sys.stderr.write("after main2") # (.. even if curseswin runs fine ..)
推荐答案
这要在不涉及父进程的情况下完成.幸运的是，有一种方法可以使用
This can't be done without getting the parent process involved. Fortunately, there's a way to get bash involved using I/O redirection :
$ (echo "foo" | ./pipe.py) 3<&0
这将把foo传送到子外壳中的pipe.py，并将stdin复制到文件描述符3中.现在我们要做的就是在python脚本中使用来自父进程的额外帮助(因为我们将继承fd 3):
That will pipe foo to pipe.py in a subshell with stdin duplicated into file descriptor 3. Now all we need to do is use that extra help from our parent process in the python script (since we'll inherit fd 3):
#!/usr/bin/env python
import sys, os
import curses
output = sys.stdin.readline(100)
# We're finished with stdin. Duplicate inherited fd 3,
# which contains a duplicate of the parent process' stdin,
# into our stdin, at the OS level (assigning os.fdopen(3)
# to sys.stdin or sys.__stdin__ does not work).
os.dup2(3, 0)
# Now curses can initialize.
screen = curses.initscr()
screen.border(0)
screen.addstr(12, 25, output)
screen.refresh()
screen.getch()
curses.endwin()
最后，您可以通过首先运行子shell来解决命令行中的丑陋语法:
Finally, you can work around the ugly syntax on the command line by running the subshell first:
$ exec 3<&0 # spawn subshell
$ echo "foo" | ./pipe.py # works
$ echo "bar" | ./pipe.py # still works
如果您有bash，就可以解决您的问题.
That solves your problem, if you have bash.
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