From: Gregory P. Smith <greg@mad-scientist.com>
Date: Sat, 5 Feb 2011 21:47:25 +0000 (+0000)
Subject: issue7678 - Properly document how to replace a shell pipeline so that SIGPIPE
X-Git-Tag: v3.2rc3~41
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=e09d2f1614e96c98b55692281cf2d2be49e9c881;p=thirdparty%2FPython%2Fcpython.git

issue7678 - Properly document how to replace a shell pipeline so that SIGPIPE
happens when the end exits before the beginning.
---

diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index e08dc8e95ee3..bcd38de3e3cb 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -519,8 +519,11 @@ Replacing shell pipeline
    ==>
    p1 = Popen(["dmesg"], stdout=PIPE)
    p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
+   p1.stdout.close()  # Allow p1 to receive a SIGPIPE if p2 exits.
    output = p2.communicate()[0]
 
+The p1.stdout.close() call after starting the p2 is important in order for p1
+to receive a SIGPIPE if p2 exits before p1.
 
 Replacing :func:`os.system`
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^