ipc::cmd.3

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.ie n .Sh "$bool = IPC::Cmd\->can_capture_buffer"
.el .Sh "\f(CW$bool\fP = IPC::Cmd\->can_capture_buffer"
.IX Subsection "$bool = IPC::Cmd->can_capture_buffer"
Utility function that tells you if \f(CW\*(C`IPC::Cmd\*(C'\fR is capable of
capturing buffers in it's current configuration.
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
.ie n .Sh "$path = can_run( \s-1PROGRAM\s0 );"
.el .Sh "\f(CW$path\fP = can_run( \s-1PROGRAM\s0 );"
.IX Subsection "$path = can_run( PROGRAM );"
\&\f(CW\*(C`can_run\*(C'\fR takes but a single argument: the name of a binary you wish
to locate. \f(CW\*(C`can_run\*(C'\fR works much like the unix binary \f(CW\*(C`which\*(C'\fR or the bash
command \f(CW\*(C`type\*(C'\fR, which scans through your path, looking for the requested
binary .
.PP
Unlike \f(CW\*(C`which\*(C'\fR and \f(CW\*(C`type\*(C'\fR, this function is platform independent and
will also work on, for example, Win32.
.PP
It will return the full path to the binary you asked for if it was
found, or \f(CW\*(C`undef\*(C'\fR if it was not.
.ie n .Sh "$ok\fP | ($ok, \f(CW$err\fP, \f(CW$full_buf\fP, \f(CW$stdout_buff\fP, \f(CW$stderr_buff) = run( command => \s-1COMMAND\s0, [verbose => \s-1BOOL\s0, buffer => \e$SCALAR] );"
.el .Sh "\f(CW$ok\fP | ($ok, \f(CW$err\fP, \f(CW$full_buf\fP, \f(CW$stdout_buff\fP, \f(CW$stderr_buff\fP) = run( command => \s-1COMMAND\s0, [verbose => \s-1BOOL\s0, buffer => \e$SCALAR] );"
.IX Subsection "$ok | ($ok, $err, $full_buf, $stdout_buff, $stderr_buff) = run( command => COMMAND, [verbose => BOOL, buffer => $SCALAR] );"
\&\f(CW\*(C`run\*(C'\fR takes 3 arguments:
.IP "command" 4
.IX Item "command"
This is the command to execute. It may be either a string or an array
reference.
This is a required argument.
.Sp
See \s-1CAVEATS\s0 for remarks on how commands are parsed and their
limitations.
.IP "verbose" 4
.IX Item "verbose"
This controls whether all output of a command should also be printed
to \s-1STDOUT/STDERR\s0 or should only be trapped in buffers (\s-1NOTE:\s0 buffers
require \f(CW\*(C`IPC::Run\*(C'\fR to be installed or your system able to work with
\&\f(CW\*(C`IPC::Open3\*(C'\fR).
.Sp
It will default to the global setting of \f(CW$IPC::Cmd::VERBOSE\fR,
which by default is 0.
.IP "buffer" 4
.IX Item "buffer"
This will hold all the output of a command. It needs to be a reference
to a scalar.
Note that this will hold both the \s-1STDOUT\s0 and \s-1STDERR\s0 messages, and you
have no way of telling which is which.
If you require this distinction, run the \f(CW\*(C`run\*(C'\fR command in list context
and inspect the individual buffers.
.Sp
Of course, this requires that the underlying call supports buffers. See
the note on buffers right above.
.PP
\&\f(CW\*(C`run\*(C'\fR will return a simple \f(CW\*(C`true\*(C'\fR or \f(CW\*(C`false\*(C'\fR when called in scalar
context.
In list context, you will be returned a list of the following items:
.IP "success" 4
.IX Item "success"
A simple boolean indicating if the command executed without errors or
not.
.IP "errorcode" 4
.IX Item "errorcode"
If the first element of the return value (success) was 0, then some
error occurred. This second element is the error code the command
you requested exited with, if available.
.IP "full_buffer" 4
.IX Item "full_buffer"
This is an arrayreference containing all the output the command
generated.
Note that buffers are only available if you have \f(CW\*(C`IPC::Run\*(C'\fR installed,
or if your system is able to work with \f(CW\*(C`IPC::Open3\*(C'\fR \*(-- See below).
This element will be \f(CW\*(C`undef\*(C'\fR if this is not the case.
.IP "out_buffer" 4
.IX Item "out_buffer"
This is an arrayreference containing all the output sent to \s-1STDOUT\s0 the
command generated.
Note that buffers are only available if you have \f(CW\*(C`IPC::Run\*(C'\fR installed,
or if your system is able to work with \f(CW\*(C`IPC::Open3\*(C'\fR \*(-- See below).
This element will be \f(CW\*(C`undef\*(C'\fR if this is not the case.
.IP "error_buffer" 4
.IX Item "error_buffer"
This is an arrayreference containing all the output sent to \s-1STDERR\s0 the
command generated.
Note that buffers are only available if you have \f(CW\*(C`IPC::Run\*(C'\fR installed,
or if your system is able to work with \f(CW\*(C`IPC::Open3\*(C'\fR \*(-- See below).
This element will be \f(CW\*(C`undef\*(C'\fR if this is not the case.
.PP
See the \f(CW\*(C`HOW IT WORKS\*(C'\fR Section below to see how \f(CW\*(C`IPC::Cmd\*(C'\fR decides
what modules or function calls to use when issuing a command.
.SH "HOW IT WORKS"
.IX Header "HOW IT WORKS"
\&\f(CW\*(C`run\*(C'\fR will try to execute your command using the following logic:
.IP "\(bu" 4
If you have \f(CW\*(C`IPC::Run\*(C'\fR installed, and the variable \f(CW$IPC::Cmd::USE_IPC_RUN\fR
is set to true (See the \f(CW\*(C`GLOBAL VARIABLES\*(C'\fR Section) use that to execute 
the command. You will have the full output available in buffers, interactive commands are sure to work  and you are guaranteed to have your verbosity
settings honored cleanly.
.IP "\(bu" 4
Otherwise, if the variable \f(CW$IPC::Cmd::USE_IPC_OPEN3\fR is set to true 
(See the \f(CW\*(C`GLOBAL VARIABLES\*(C'\fR Section), try to execute the command using
\&\f(CW\*(C`IPC::Open3\*(C'\fR. Buffers will be available on all platforms except \f(CW\*(C`Win32\*(C'\fR,
interactive commands will still execute cleanly, and also your verbosity
settings will be adhered to nicely;
.IP "\(bu" 4
Otherwise, if you have the verbose argument set to true, we fall back
to a simple \fIsystem()\fR call. We cannot capture any buffers, but
interactive commands will still work.
.IP "\(bu" 4
Otherwise we will try and temporarily redirect \s-1STDERR\s0 and \s-1STDOUT\s0, do a
\&\fIsystem()\fR call with your command and then re-open \s-1STDERR\s0 and \s-1STDOUT\s0.
This is the method of last resort and will still allow you to execute
your commands cleanly. However, no buffers will be available.
.SH "Global Variables"
.IX Header "Global Variables"
The behaviour of IPC::Cmd can be altered by changing the following
global variables:
.ie n .Sh "$IPC::Cmd::VERBOSE"
.el .Sh "\f(CW$IPC::Cmd::VERBOSE\fP"
.IX Subsection "$IPC::Cmd::VERBOSE"
This controls whether IPC::Cmd will print any output from the
commands to the screen or not. The default is 0;
.ie n .Sh "$IPC::Cmd::USE_IPC_RUN"
.el .Sh "\f(CW$IPC::Cmd::USE_IPC_RUN\fP"
.IX Subsection "$IPC::Cmd::USE_IPC_RUN"
This variable controls whether IPC::Cmd will try to use IPC::Run
when available and suitable. Defaults to true if you are on \f(CW\*(C`Win32\*(C'\fR.
.ie n .Sh "$IPC::Cmd::USE_IPC_OPEN3"
.el .Sh "\f(CW$IPC::Cmd::USE_IPC_OPEN3\fP"
.IX Subsection "$IPC::Cmd::USE_IPC_OPEN3"
This variable controls whether IPC::Cmd will try to use IPC::Open3
when available and suitable. Defaults to true.
.ie n .Sh "$IPC::Cmd::WARN"
.el .Sh "\f(CW$IPC::Cmd::WARN\fP"
.IX Subsection "$IPC::Cmd::WARN"
This variable controls whether run time warnings should be issued, like
the failure to load an \f(CW\*(C`IPC::*\*(C'\fR module you explicitly requested.
.PP
Defaults to true. Turn this off at your own risk.
.SH "Caveats"
.IX Header "Caveats"
.IP "Whitespace" 4
.IX Item "Whitespace"
When you provide a string as this argument, the string will be
split on whitespace to determine the individual elements of your
command. Although this will usually just Do What You Mean, it may
break if you have files or commands with whitespace in them.
.Sp
If you do not wish this to happen, you should provide an array
reference, where all parts of your command are already separated out.
Note however, if there's extra or spurious whitespace in these parts,
the parser or underlying code may not interpret it correctly, and
cause an error.
.Sp
Example:
The following code
.Sp
.Vb 1
\&    gzip \-cdf foo.tar.gz | tar \-xf \-
.Ve
.Sp
should either be passed as
.Sp
.Vb 1
\&    "gzip \-cdf foo.tar.gz | tar \-xf \-"
.Ve
.Sp
or as
.Sp
.Vb 1
\&    [\*(Aqgzip\*(Aq, \*(Aq\-cdf\*(Aq, \*(Aqfoo.tar.gz\*(Aq, \*(Aq|\*(Aq, \*(Aqtar\*(Aq, \*(Aq\-xf\*(Aq, \*(Aq\-\*(Aq]
.Ve
.Sp
But take care not to pass it as, for example
.Sp
.Vb 1
\&    [\*(Aqgzip \-cdf foo.tar.gz\*(Aq, \*(Aq|\*(Aq, \*(Aqtar \-xf \-\*(Aq]
.Ve
.Sp
Since this will lead to issues as described above.
.IP "\s-1IO\s0 Redirect" 4
.IX Item "IO Redirect"
Currently it is too complicated to parse your command for \s-1IO\s0
Redirections. For capturing \s-1STDOUT\s0 or \s-1STDERR\s0 there is a work around
however, since you can just inspect your buffers for the contents.
.SH "See Also"
.IX Header "See Also"
\&\f(CW\*(C`IPC::Run\*(C'\fR, \f(CW\*(C`IPC::Open3\*(C'\fR
.SH "ACKNOWLEDGEMENTS"
.IX Header "ACKNOWLEDGEMENTS"
Thanks to James Mastros and Martijn van der Streek for their
help in getting IPC::Open3 to behave nicely.
.SH "BUG REPORTS"
.IX Header "BUG REPORTS"
Please report bugs or other issues to <bug\-ipc\[e-mail]>.
.SH "AUTHOR"
.IX Header "AUTHOR"
This module by Jos Boumans <[e-mail]>.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
This library is free software; you may redistribute and/or modify it 
under the same terms as Perl itself.