模拟bash进程替换：
#!/usr/bin/env python
from subprocess import check_call
check_call('someprogram <(someprocess) <(anotherprocess)',
shell=True, executable='/bin/bash')
在Python中，您可以使用命名管道：
#!/usr/bin/env python
from subprocess import Popen
with named_pipes(n=2) as paths:
someprogram = Popen(['someprogram'] + paths)
processes = []
for path, command in zip(paths, ['someprocess', 'anotherprocess']):
with open(path, 'wb', 0) as pipe:
processes.append(Popen(command, stdout=pipe, close_fds=True))
for p in [someprogram] + processes:
p.wait()
在哪里named_pipes(n)：
import os
import shutil
import tempfile
from contextlib import contextmanager
@contextmanager
def named_pipes(n=1):
dirname = tempfile.mkdtemp()
try:
paths = [os.path.join(dirname, 'named_pipe' + str(i)) for i in range(n)]
for path in paths:
os.mkfifo(path)
yield paths
finally:
shutil.rmtree(dirname)
实现bash进程替换的另一种更可取的方式（无需在磁盘上创建命名条目）是使用@Dunes建议的/dev/fd/N文件名（如果可用）。在FreeBSD上，（）为进程打开的所有文件描述符创建条目。要测试可用性，请运行：@L_419_4@fdescfs(5)/dev/fd/#
$ test -r /dev/fd/3 3</dev/null && echo /dev/fd is available
如果失败；尝试进行符号链接/dev/fd ，proc(5)就像在某些Linux上所做的那样：
$ ln -s /proc/self/fd /dev/fd
这是/dev/fd基于someprogram <(someprocess) <(anotherprocess)bash命令的实现：
#!/usr/bin/env python3
from contextlib import ExitStack
from subprocess import CalledProcessError, Popen, PIPE
def kill(process):
if process.poll() is None: # still running
process.kill()
with ExitStack() as stack: # for proper cleanup
processes = []
for command in [['someprocess'], ['anotherprocess']]: # start child processes
processes.append(stack.enter_context(Popen(command, stdout=PIPE)))
stack.callback(kill, processes[-1]) # kill on someprogram exit
fds = [p.stdout.fileno() for p in processes]
someprogram = stack.enter_context(
Popen(['someprogram'] + ['/dev/fd/%d' % fd for fd in fds], pass_fds=fds))
for p in processes: # close pipes in the parent
p.stdout.close()
# exit stack: wait for processes
if someprogram.returncode != 0: # errors shouldn't go unnoticed
raise CalledProcessError(someprogram.returncode, someprogram.args)
注意：在我的Ubuntu机器上，该subprocess代码仅在Python 3.4+中有效，尽管pass_fds自Python 3.2起可用。
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