IO::CaptureOutput - capture STDOUT and STDERR from Perl code, subprocesses or XS
version 1.1104
use IO::CaptureOutput qw(capture qxx qxy);
# STDOUT and STDERR separately
capture { noisy_sub(@args) } \$stdout, \$stderr;
# STDOUT and STDERR together
capture { noisy_sub(@args) } \$combined, \$combined;
# STDOUT and STDERR from external command
($stdout, $stderr, $success) = qxx( @cmd );
# STDOUT and STDERR together from external command
($combined, $success) = qxy( @cmd );
This module is no longer recommended by the maintainer - see
the Capture::Tiny manpage instead.
This module provides routines for capturing STDOUT and STDERR from perl
subroutines, forked system calls (e.g. system(), fork()) and from XS
or C modules.
The following functions will be exported on demand.
capture \&subroutine, \$stdout, \$stderr;
Captures everything printed to STDOUT and STDERR for the duration of
&subroutine. $stdout and $stderr are optional scalars that will
contain STDOUT and STDERR respectively.
capture() uses a code prototype so the first argument can be specified
directly within brackets if desired.
# shorthand with prototype
capture C< print __PACKAGE__ > \$stdout, \$stderr;
Returns the return value(s) of &subroutine. The sub is called in the
same context as capture() was called e.g.:
@rv = capture C< wantarray > ; # returns true
$rv = capture C< wantarray > ; # returns defined, but not true
capture C< wantarray >; # void, returns undef
capture() is able to capture output from subprocesses and C code, which
traditional tie() methods of output capture are unable to do.
Note: capture() will only capture output that has been written or
flushed to the filehandle.
If the two scalar references refer to the same scalar, then STDERR will
be merged to STDOUT before capturing and the scalar will hold the
combined output of both.
capture \&subroutine, \$combined, \$combined;
Normally, capture() uses anonymous, temporary files for capturing
output. If desired, specific file names may be provided instead as
additional options.
capture \&subroutine, \$stdout, \$stderr, $out_file, $err_file;
Files provided will be clobbered, overwriting any previous data, but will
persist after the call to capture() for inspection or other
manipulation.
By default, when no references are provided to hold STDOUT or STDERR,
output is captured and silently discarded.
# Capture STDOUT, discard STDERR
capture \&subroutine, \$stdout;
# Discard STDOUT, capture STDERR
capture \&subroutine, undef, \$stderr;
However, even when using undef, output can be captured to specific
files.
# Capture STDOUT to a specific file, discard STDERR
capture \&subroutine, \$stdout, undef, $outfile;
# Discard STDOUT, capture STDERR to a specific file
capture \&subroutine, undef, \$stderr, undef, $err_file;
# Discard both, capture merged output to a specific file
capture \&subroutine, undef, undef, $mergedfile;
It is a fatal error to merge STDOUT and STDERR and request separate,
specific files for capture.
# ERROR:
capture \&subroutine, \$stdout, \$stdout, $out_file, $err_file;
capture \&subroutine, undef, undef, $out_file, $err_file;
If either STDOUT or STDERR should be passed through to the terminal instead
of captured, provide a reference to undef -- \undef -- instead of a
capture variable.
# Capture STDOUT, display STDERR
capture \&subroutine, \$stdout, \undef;
# Display STDOUT, capture STDERR
capture \&subroutine, \undef, \$stderr;
($stdout, $stderr, $success, $exit_code) = capture_exec(@args);
Captures and returns the output from system(@args). In scalar context,
capture_exec() will return what was printed to STDOUT. In list
context, it returns what was printed to STDOUT and STDERR as well as
a success flag and the exit value.
$stdout = capture_exec('perl', '-e', 'print "hello world"');
($stdout, $stderr, $success, $exit_code) =
capture_exec('perl', '-e', 'warn "Test"');
capture_exec passes its arguments to system() and on MSWin32 will
protect arguments with shell quotes if necessary. This makes it a handy
and slightly more portable alternative to backticks, piped open() and
IPC::Open3.
The $success flag returned will be true if the command ran successfully
and false if it did not (if the command could not be run or if it ran and
returned a non-zero exit value). On failure, the raw exit value of the
system() call is available both in the $exit_code returned and in the
$? variable.
($stdout, $stderr, $success, $exit_code) =
capture_exec('perl', '-e', 'warn "Test" and exit 1');
if ( ! $success ) {
print "The exit code was " . ($exit_code >> 8) . "\n";
}
See perlvar for more information on interpreting a child process exit
code.
($combined, $success, $exit_code) = capture_exec_combined(
'perl', '-e', 'print "hello\n"', 'warn "Test\n"
);
This is just like capture_exec(), except that it merges STDERR with
STDOUT before capturing output.
Note: there is no guarantee that text printed to STDOUT and STDERR
in the subprocess will be appear in order. The actual order will depend on
how IO buffering is handled in the subprocess.
This is an alias for capture_exec().
This is an alias for capture_exec_combined().
Please report any bugs or feature requests through the issue tracker
at https://github.com/dagolden/IO-CaptureOutput/issues.
You will be notified automatically of any progress on your issue.
This is open source software. The code repository is available for
public review and contribution under the terms of the license.
https://github.com/dagolden/IO-CaptureOutput
git clone https://github.com/dagolden/IO-CaptureOutput.git
This software is copyright (c) 2015 by Simon Flack and David Golden.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
|