IPC::Run3 - run a subprocess in batch mode (a la system) on Unix, Win32, etc.
version 0.039
use IPC::Run3; # Exports run3() by default
run3 \@cmd, \$in, \$out, \$err;
run3 \@cmd, \@in, \&out, \$err;
This module allows you to run a subprocess and redirect stdin, stdout, and/or stderr to files and perl data structures. It aims to satisfy 99% of the need for using system, qx, and open3 with a simple, extremely Perlish API and none of the bloat and rarely used features of IPC::Run.
Speed, simplicity, and portability are paramount. (That's speed of Perl code; which is often much slower than the kind of buffered I/O that this module uses to spool input to and output from the child command.) Disk space is not.
run3(\@cmd, INPUT, OUTPUT, \$err)Note that passing in a reference to undef explicitly redirects the associated file descriptor for STDIN, STDOUT, or STDERR from or to the local equivalent of /dev/null (this does not pass a closed filehandle). Passing in undef (or not passing a redirection) allows the child to inherit the corresponding STDIN, STDOUT, or STDERR from the parent.
Because the redirects come last, this allows STDOUT and STDERR to default to the parent's by just not specifying them -- a common use case.
Note: This means that:
run3 \@cmd, undef, \$out; # Pass on parent's STDIN
does not close the child's STDIN, it passes on the parent's. Use
run3 \@cmd, \undef, \$out; # Close child's STDIN
for that. It's not ideal, but it does work.
If the exact same value is passed for $stdout and $stderr, then the child will write both to the same filehandle. In general, this means that
run3 \@cmd, \undef, "foo.txt", "foo.txt";
run3 \@cmd, \undef, \$both, \$both;
will DWYM and pass a single file handle to the child for both STDOUT and STDERR, collecting all into $both.
run3 returns true if the command executes and throws an exception otherwise. It should leave $? intact for inspection of exit and wait status.
To enable debugging use the IPCRUN3DEBUG environment variable to a non-zero integer value:
$ IPCRUN3DEBUG=1 myapp
To enable profiling, set IPCRUN3PROFILE to a number to enable emitting profile information to STDERR (1 to get timestamps, 2 to get a summary report at the END of the program, 3 to get mini reports after each run) or to a filename to emit raw data to a file for later analysis.
Here's how it stacks up to existing APIs:
system(), qx'', open "...|", open "|...":run3 ["foo"]; # does not invoke shell
open2(), open3():IPC::Run::run():pty support
Often uses intermediate files (determined by File::Temp, and thus by the File::Spec defaults and the TMPDIR env. variable) for speed, portability and simplicity.
Use extrem caution when using run3 in a threaded environment if concurrent calls of run3 are possible. Most likely, I/O from different invocations will get mixed up. The reason is that in most thread implementations all threads in a process share the same STDIN/STDOUT/STDERR. Known failures are Perl ithreads on Linux and Win32. Note that fork on Win32 is emulated via Win32 threads and hence I/O mix up is possible between forked children here (run3 is "fork safe" on Unix, though).
Copyright 2003, R. Barrie Slaymaker, Jr., All Rights Reserved
You may use this module under the terms of the BSD, Artistic, or GPL licenses, any version.
Barrie Slaymaker <barries@slaysys.com>
Ricardo SIGNES <rjbs@cpan.org> performed some routine maintenance in 2005, thanks to help from the following ticket and/or patch submitters: Jody Belka, Roderich Schupp, David Morel, and anonymous others.
