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.

METHODS

       spawn
           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.

       wait_child
           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 fail with an error message.

AUTHORS

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

SEE ALSO

       Dpkg, Dpkg::ErrorHandling