Dpkg::IPC (3) - Linux Manuals

Dpkg::IPC: helper functions for IPC

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.

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

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.

CHANGES

Version 1.01

New options: spawn() now accepts 'sig' and 'delete_sig'.

Version 1.00

Mark the module as public.

AUTHORS

Written by Raphaël Hertzog <hertzog [at] debian.org> and Frank Lichtenheld <djpig [at] debian.org>.