Integrate with Sarathy.

[perl5.git] / pod / perlipc.pod

diff --git a/pod/perlipc.pod b/pod/perlipc.pod
index cc2a1a9..e687304 100644 (file)
--- a/pod/perlipc.pod
+++ b/pod/perlipc.pod
@@ -56,7 +56,17 @@ So to check whether signal 17 and SIGALRM were the same, do just this:
 
 You may also choose to assign the strings C<'IGNORE'> or C<'DEFAULT'> as
 the handler, in which case Perl will try to discard the signal or do the
-default thing.  Some signals can be neither trapped nor ignored, such as
+default thing.
+
+On most Unix platforms, the C<CHLD> (sometimes also known as C<CLD>) signal
+has special behavior with respect to a value of C<'IGNORE'>.
+Setting C<$SIG{CHLD}> to C<'IGNORE'> on such a platform has the effect of
+not creating zombie processes when the parent process fails to C<wait()>
+on its child processes (i.e. child processes are automatically reaped).
+Calling C<wait()> with C<$SIG{CHLD}> set to C<'IGNORE'> usually returns
+C<-1> on such platforms.
+
+Some signals can be neither trapped nor ignored, such as
 the KILL and STOP (but not the TSTP) signals.  One strategy for
 temporarily ignoring signals is to use a local() statement, which will be
 automatically restored once your block is exited.  (Remember that local()
@@ -266,7 +276,7 @@ same effect as opening a pipe for reading:
 
 While this is true on the surface, it's much more efficient to process the
 file one line or record at a time because then you don't have to read the
-whole thing into memory at once. It also gives you finer control of the
+whole thing into memory at once.  It also gives you finer control of the
 whole process, letting you to kill off the child process early if you'd
 like.
 
@@ -297,8 +307,7 @@ To catch it, you could use this:
 
 Both the main process and any child processes it forks share the same
 STDIN, STDOUT, and STDERR filehandles.  If both processes try to access
-them at once, strange things can happen.  You'll certainly want to any
-stdio flush output buffers before forking.  You may also want to close
+them at once, strange things can happen.  You may also want to close
 or reopen the filehandles for the child.  You can get around this by
 opening your pipe with open(), but on some systems this means that the
 child process cannot outlive the parent.
@@ -463,7 +472,6 @@ Here's an example of using open2():
     use FileHandle;
     use IPC::Open2;
     $pid = open2(*Reader, *Writer, "cat -u -n" );
-    Writer->autoflush(); # default here, actually
     print Writer "stuff\n";
     $got = <Reader>;
 
@@ -1149,7 +1157,7 @@ server. (Under Unix, ports under 1024 are restricted to the
 superuser.)  In our sample, we'll use port 9000, but you can use
 any port that's not currently in use on your system.  If you try
 to use one already in used, you'll get an "Address already in use"
-message. Under Unix, the C<netstat -a> command will show
+message.  Under Unix, the C<netstat -a> command will show
 which services current have servers.
 
 =item Listen
@@ -1181,7 +1189,7 @@ you'll have to use the C<sysread> variant of the interactive client above.
 This server accepts one of five different commands, sending output
 back to the client.  Note that unlike most network servers, this one
 only handles one incoming client at a time.  Multithreaded servers are
-covered in Chapter 6 of the Camel as well as later in this manpage.
+covered in Chapter 6 of the Camel.
 
 Here's the code.  We'll