diff options
Diffstat (limited to 'Master/tlpkg/tlperl/lib/IPC/Open2.pm')
-rw-r--r-- | Master/tlpkg/tlperl/lib/IPC/Open2.pm | 46 |
1 files changed, 25 insertions, 21 deletions
diff --git a/Master/tlpkg/tlperl/lib/IPC/Open2.pm b/Master/tlpkg/tlperl/lib/IPC/Open2.pm index 9e27144571d..cd330507990 100644 --- a/Master/tlpkg/tlperl/lib/IPC/Open2.pm +++ b/Master/tlpkg/tlperl/lib/IPC/Open2.pm @@ -6,7 +6,7 @@ our ($VERSION, @ISA, @EXPORT); require 5.000; require Exporter; -$VERSION = 1.04; +$VERSION = 1.05; @ISA = qw(Exporter); @EXPORT = qw(open2); @@ -18,38 +18,42 @@ IPC::Open2 - open a process for both reading and writing using open2() use IPC::Open2; - $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'some cmd and args'); - # or without using the shell - $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'some', 'cmd', 'and', 'args'); + my $pid = open2(my $chld_out, my $chld_in, + 'some', 'cmd', 'and', 'args'); + # or passing the command through the shell + my $pid = open2(my $chld_out, my $chld_in, 'some cmd and args'); - # or with handle autovivification - my($chld_out, $chld_in); - $pid = open2($chld_out, $chld_in, 'some cmd and args'); - # or without using the shell - $pid = open2($chld_out, $chld_in, 'some', 'cmd', 'and', 'args'); + # read from parent STDIN and write to already open handle + open my $outfile, '>', 'outfile.txt' or die "open failed: $!"; + my $pid = open2($outfile, '<&STDIN', 'some', 'cmd', 'and', 'args'); + # read from already open handle and write to parent STDOUT + open my $infile, '<', 'infile.txt' or die "open failed: $!"; + my $pid = open2('>&STDOUT', $infile, 'some', 'cmd', 'and', 'args'); + + # reap zombie and retrieve exit status waitpid( $pid, 0 ); my $child_exit_status = $? >> 8; =head1 DESCRIPTION -The open2() function runs the given $cmd and connects $chld_out for +The open2() function runs the given command and connects $chld_out for reading and $chld_in for writing. It's what you think should work when you try - $pid = open(HANDLE, "|cmd args|"); + my $pid = open(my $fh, "|cmd args|"); -The write filehandle will have autoflush turned on. +The $chld_in filehandle will have autoflush turned on. If $chld_out is a string (that is, a bareword filehandle rather than a glob or a reference) and it begins with C<< >& >>, then the child will send output directly to that file handle. If $chld_in is a string that begins with C<< <& >>, then $chld_in will be closed in the parent, and the child will -read from it directly. In both cases, there will be a dup(2) instead of a -pipe(2) made. +read from it directly. In both cases, there will be a L<dup(2)> instead of a +L<pipe(2)> made. -If either reader or writer is the null string, this will be replaced -by an autogenerated filehandle. If so, you must pass a valid lvalue +If either reader or writer is the empty string or undefined, this will be +replaced by an autogenerated filehandle. If so, you must pass a valid lvalue in the parameter slot so it can be overwritten in the caller, or an exception will be raised. @@ -66,10 +70,10 @@ Failing to do this can result in an accumulation of defunct or "zombie" processes. See L<perlfunc/waitpid> for more information. This whole affair is quite dangerous, as you may block forever. It -assumes it's going to talk to something like B<bc>, both writing +assumes it's going to talk to something like L<bc(1)>, both writing to it and reading from it. This is presumably safe because you -"know" that commands like B<bc> will read a line at a time and -output a line at a time. Programs like B<sort> that read their +"know" that commands like L<bc(1)> will read a line at a time and +output a line at a time. Programs like L<sort(1)> that read their entire input stream first, however, are quite apt to cause deadlock. The big problem with this approach is that if you don't have control @@ -77,8 +81,8 @@ over source code being run in the child process, you can't control what it does with pipe buffering. Thus you can't just open a pipe to C<cat -v> and continually read and write a line from it. -The IO::Pty and Expect modules from CPAN can help with this, as they -provide a real tty (well, a pseudo-tty, actually), which gets you +The L<IO::Pty> and L<Expect> modules from CPAN can help with this, as +they provide a real tty (well, a pseudo-tty, actually), which gets you back to line buffering in the invoked command again. =head1 WARNING |