NAME

       Dpkg::IPC - helper functions for IPC

DESCRIPTION

       Dpkg::IPC offers helper functions to allow you to execute other programs in an easy, yet flexible way,
       while hiding all the gory details of IPC (Inter-Process Communication) from you.

FUNCTIONS

       $pid = spawn(%opts)
           Creates a child process and executes another program in it.  The arguments are interpreted as a hash
           of options, specifying how to handle the in and output of the program to execute.  Returns the pid of
           the child process (unless the wait_child option was given).

           Any error will cause the function to exit with one of the Dpkg::ErrorHandling functions.

           Options:

           exec
               Can be either a scalar, i.e. the name of the program to be executed, or an array reference, i.e.
               the name of the program plus additional arguments. Note that the program will never be executed
               via the shell, so you can't specify additional arguments in the scalar string and you can't use
               any shell facilities like globbing.

               Mandatory Option.

           from_file, to_file, error_to_file
               Filename as scalar. Standard input/output/error of the child process will be redirected to the
               file specified.

           from_handle, to_handle, error_to_handle
               Filehandle. Standard input/output/error of the child process will be dup'ed from the handle.

           from_pipe, to_pipe, error_to_pipe
               Scalar reference or object based on IO::Handle. A pipe will be opened for each of the two options
               and either the reading ("to_pipe" and "error_to_pipe") or the writing end ("from_pipe") will be
               returned in the referenced scalar. Standard input/output/error of the child process will be
               dup'ed to the other ends of the pipes.

           from_string, to_string, error_to_string
               Scalar reference. Standard input/output/error of the child process will be redirected to the
               string given as reference. Note that it wouldn't be strictly necessary to use a scalar reference
               for "from_string", as the string is not modified in any way. This was chosen only for reasons of
               symmetry with "to_string" and "error_to_string". "to_string" and "error_to_string" imply the
               "wait_child" option.

           wait_child
               Scalar. If containing a true value, wait_child() will be called before returning. The return
               value of spawn() will be a true value, not the pid.

           nocheck
               Scalar. Option of the wait_child() call.

           timeout
               Scalar. Option of the wait_child() call.

           chdir
               Scalar. The child process will chdir in the indicated directory before calling exec.

           env Hash reference. The child process will populate %ENV with the items of the hash before calling
               exec. This allows exporting environment variables.

           delete_env
               Array reference. The child process will remove all environment variables listed in the array
               before calling exec.

           sig Hash reference. The child process will populate %SIG with the items of the hash before calling
               exec. This allows setting signal dispositions.

           delete_sig
               Array reference. The child process will reset all signals listed in the array to their default
               dispositions before calling exec.

       wait_child($pid, %opts)
           Takes as first argument the pid of the process to wait for.  Remaining arguments are taken as a hash
           of options. Returns nothing. Fails if the child has been ended by a signal or if it exited non-zero.

           Options:

           cmdline
               String to identify the child process in error messages.  Defaults to "child process".

           nocheck
               If true do not check the return status of the child (and thus do not fail it it has been killed
               or if it exited with a non-zero return code).

           timeout
               Set a maximum time to wait for the process, after that kill the process and fail with an error
               message.

CHANGES

   Version 1.02 (dpkg 1.18.0)
       Change options: wait_child() now kills the process when reaching the 'timeout'.

   Version 1.01 (dpkg 1.17.11)
       New options: spawn() now accepts 'sig' and 'delete_sig'.

   Version 1.00 (dpkg 1.15.6)
       Mark the module as public.

AUTHORS

       Written by Raphaël Hertzog <hertzog@debian.org> and Frank Lichtenheld <djpig@debian.org>.

SEE ALSO

       Dpkg, Dpkg::ErrorHandling