显然这几乎是“Bad pipe filedescriptor when reading from stdin in python – Stack Overflow”的重复;但是,我认为这种情况稍微复杂一些(并且它不是Windows特定的,因为该线程的结论是).
我目前正在尝试用Python编写一个简单的脚本：我想为脚本提供输入 – 通过命令行参数;或者通过“管道”字符串到此脚本 – 并让脚本使用curses终端接口显示此输入字符串.
完整的脚本,这里称为testcurses.py,如下所示.问题是每当我尝试实际的管道时,这似乎搞乱了stdin,而curses窗口从未显示过.这是一个终端输出：
## CASE 1: THROUGH COMMAND LINE ARGUMENT (arg being stdin):
##
$./testcurses.py -
['-'] 1
stdout/stdin (obj): opening -
obj Syntax as in SO1057638,like:
## python -c "print 'TYPING blabla HERE'" | python testcurses.py -
##
$echo "TYPING blabla HERE" | ./testcurses.py -
['-'] 1
stdout/stdin (obj): opening -
obj nothing is shown
# ################
据我所知,问题是： – 每当我们将字符串传递给Python脚本时,Python脚本就会失去对终端的引用作为stdin,并注意到被替换的stdin不再是termios结构 – 并且因为stdin是不再是终端,curses.initscr()立即退出而不渲染任何东西.
所以,我的问题是 – 简而言之：我可以以某种方式实现,语法echo“blabla”| ./testcurses.py – 最终在curses中显示管道字符串？更具体地说：是否可以从Python脚本中检索对调用终端的stdin的引用,即使此脚本被“管道”到？
提前感谢任何指针,
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,# 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 ..)
最佳答案
如果不涉及父进程,则无法完成此操作.幸运的是,有一种方法可以使用I/O redirection获得bash：
$(echo "foo" | ./pipe.py) 3<&0
这会将foo管道传递到子shell中的pipe.py,并将stdin复制到文件描述符3.现在我们需要做的就是在python脚本中使用父进程的额外帮助(因为我们将继承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,output)
screen.refresh()
screen.getch()
curses.endwin()
最后,您可以通过首先运行子shell来解决命令行上的丑陋语法：
$exec 3<&0 # spawn subshell
$echo "foo" | ./pipe.py # works
$echo "bar" | ./pipe.py # still works
如果你有bash,那就解决了你的问题.
