Class: Gio::SubprocessLauncher

Inherits:
Object
  • Object
show all
Defined in:
(unknown)

Overview

This class contains a set of options for launching child processes, such as where its standard input and output will be directed, the argument list, the environment, and more.

While the #GSubprocess class has high level functions covering popular cases, use of this class allows access to more advanced options. It can also be used to launch multiple subprocesses with a similar configuration.

Instance Method Summary collapse

Instance Method Details

#cwd=(cwd) ⇒ nil

Sets the current working directory that processes will be launched with.

By default processes are launched with the current working directory of the launching process at the time of launch.

Parameters:

  • cwd (Gio::filename) —

    the cwd for launched processes

Returns:

  • (nil)

#environ=(env) ⇒ nil

Replace the entire environment of processes launched from this launcher with the given ‘environ’ variable.

Typically you will build this variable by using g_listenv() to copy the process ‘environ’ and using the functions g_environ_setenv(), g_environ_unsetenv(), etc.

As an alternative, you can use g_subprocess_launcher_setenv(), g_subprocess_launcher_unsetenv(), etc.

Pass an empty array to set an empty environment. Pass nil to inherit the parent process’ environment. As of GLib 2.54, the parent process’ environment will be copied when g_subprocess_launcher_set_environ() is called. Previously, it was copied when the subprocess was executed. This means the copied environment may now be modified (using g_subprocess_launcher_setenv(), etc.) before launching the subprocess.

On UNIX, all strings in this array can be arbitrary byte strings. On Windows, they should be in UTF-8.

Parameters:

  • env (Array<Gio::filename>) —

    the replacement environment

Returns:

  • (nil)

#flags=(flags) ⇒ Gio::SubprocessFlags

Returns flags.

Parameters:

Returns:

#getenv(variable) ⇒ Gio::filename

Returns the value of the environment variable variable in the environment of processes launched from this launcher.

On UNIX, the returned string can be an arbitrary byte string. On Windows, it will be UTF-8.

Parameters:

  • variable (Gio::filename) —

    the environment variable to get

Returns:

  • (Gio::filename) —

    the value of the environment variable, nil if unset

#new(flags) ⇒ Gio::SubprocessLauncher

Creates a new GSubprocess::Launcher.

The launcher is created with the default options. A copy of the environment of the calling process is made at the time of this call and will be used as the environment that the process is launched in.

Parameters:

Returns:

#set_child_setup(child_setup, user_data, destroy_notify) ⇒ nil

Sets up a child setup function.

The child setup function will be called after fork() but before exec() on the child’s side.

destroy_notify will not be automatically called on the child’s side of the fork(). It will only be called when the last reference on the GSubprocess::Launcher is dropped or when a new child setup function is given.

nil can be given as child_setup to disable the functionality.

Child setup functions are only available on UNIX.

Parameters:

  • child_setup (GLib::SpawnChildSetupFunc) —

    a GSpawn::ChildSetupFunc to use as the child setup function

  • user_data (GObject) —

    user data for child_setup

  • destroy_notify (GLib::DestroyNotify) —

    a GDestroy::Notify for user_data

Returns:

  • (nil)

#setenv(variable, value, overwrite) ⇒ nil

Sets the environment variable variable in the environment of processes launched from this launcher.

On UNIX, both the variable’s name and value can be arbitrary byte strings, except that the variable’s name cannot contain ‘=’. On Windows, they should be in UTF-8.

Parameters:

  • variable (Gio::filename) —

    the environment variable to set, must not contain ‘=’

  • value (Gio::filename) —

    the new value for the variable

  • overwrite (TrueClass) —

    whether to change the variable if it already exists

Returns:

  • (nil)

#spawn(error, argv0, array) ⇒ Gio::Subprocess

Creates a #GSubprocess given a provided varargs list of arguments.

Parameters:

  • error (GLib::Error) —

    Error

  • argv0 (String) —

    Command line arguments

  • array (Array) —

    Continued arguments, nil terminated

Returns:

  • (Gio::Subprocess) —

    A new #GSubprocess, or nil on error (and error will be set)

#spawnv(argv) ⇒ Gio::Subprocess

Creates a #GSubprocess given a provided array of arguments.

Parameters:

  • argv (Array<Gio::filename>) —

    Command line arguments

Returns:

  • (Gio::Subprocess) —

    A new #GSubprocess, or nil on error (and error will be set)

#stderr_file_path=(path) ⇒ nil

Sets the file path to use as the stderr for spawned processes.

If path is nil then any previously given path is unset.

The file will be created or truncated when the process is spawned, as would be the case if using ‘2>’ at the shell.

If you want to send both stdout and stderr to the same file then use %G_SUBPROCESS_FLAGS_STDERR_MERGE.

You may not set a stderr file path if a stderr fd is already set or if the launcher flags contain any flags directing stderr elsewhere.

This feature is only available on UNIX.

Parameters:

  • path (Gio::filename) —

    a filename or nil

Returns:

  • (nil)

#stdin_file_path=(path) ⇒ nil

Sets the file path to use as the stdin for spawned processes.

If path is nil then any previously given path is unset.

The file must exist or spawning the process will fail.

You may not set a stdin file path if a stdin fd is already set or if the launcher flags contain any flags directing stdin elsewhere.

This feature is only available on UNIX.

Parameters:

  • path (String)

Returns:

  • (nil)

#stdout_file_path=(path) ⇒ nil

Sets the file path to use as the stdout for spawned processes.

If path is nil then any previously given path is unset.

The file will be created or truncated when the process is spawned, as would be the case if using ‘>’ at the shell.

You may not set a stdout file path if a stdout fd is already set or if the launcher flags contain any flags directing stdout elsewhere.

This feature is only available on UNIX.

Parameters:

  • path (Gio::filename) —

    a filename or nil

Returns:

  • (nil)

#take_fd(source_fd, target_fd) ⇒ nil

Transfer an arbitrary file descriptor from parent process to the child. This function takes “ownership” of the fd; it will be closed in the parent when self is freed.

By default, all file descriptors from the parent will be closed. This function allows you to create (for example) a custom pipe() or socketpair() before launching the process, and choose the target descriptor in the child.

An example use case is GNUPG, which has a command line argument –passphrase-fd providing a file descriptor number where it expects the passphrase to be written.

Parameters:

  • source_fd (Integer) —

    File descriptor in parent process

  • target_fd (Integer) —

    Target descriptor for child process

Returns:

  • (nil)

#take_stderr_fd(fd) ⇒ nil

Sets the file descriptor to use as the stderr for spawned processes.

If fd is -1 then any previously given fd is unset.

Note that the default behaviour is to pass stderr through to the stderr of the parent process.

The passed fd belongs to the GSubprocess::Launcher. It will be automatically closed when the launcher is finalized. The file descriptor will also be closed on the child side when executing the spawned process.

You may not set a stderr fd if a stderr file path is already set or if the launcher flags contain any flags directing stderr elsewhere.

This feature is only available on UNIX.

Parameters:

  • fd (Integer) —

    a file descriptor, or -1

Returns:

  • (nil)

#take_stdin_fd(fd) ⇒ nil

Sets the file descriptor to use as the stdin for spawned processes.

If fd is -1 then any previously given fd is unset.

Note that if your intention is to have the stdin of the calling process inherited by the child then %G_SUBPROCESS_FLAGS_STDIN_INHERIT is a better way to go about doing that.

The passed fd is noted but will not be touched in the current process. It is therefore necessary that it be kept open by the caller until the subprocess is spawned. The file descriptor will also not be explicitly closed on the child side, so it must be marked O_CLOEXEC if that’s what you want.

You may not set a stdin fd if a stdin file path is already set or if the launcher flags contain any flags directing stdin elsewhere.

This feature is only available on UNIX.

Parameters:

  • fd (Integer) —

    a file descriptor, or -1

Returns:

  • (nil)

#take_stdout_fd(fd) ⇒ nil

Sets the file descriptor to use as the stdout for spawned processes.

If fd is -1 then any previously given fd is unset.

Note that the default behaviour is to pass stdout through to the stdout of the parent process.

The passed fd is noted but will not be touched in the current process. It is therefore necessary that it be kept open by the caller until the subprocess is spawned. The file descriptor will also not be explicitly closed on the child side, so it must be marked O_CLOEXEC if that’s what you want.

You may not set a stdout fd if a stdout file path is already set or if the launcher flags contain any flags directing stdout elsewhere.

This feature is only available on UNIX.

Parameters:

  • fd (Integer) —

    a file descriptor, or -1

Returns:

  • (nil)

#unsetenv(variable) ⇒ nil

Removes the environment variable variable from the environment of processes launched from this launcher.

On UNIX, the variable’s name can be an arbitrary byte string not containing ‘=’. On Windows, it should be in UTF-8.

Parameters:

  • variable (Gio::filename) —

    the environment variable to unset, must not contain ‘=’

Returns:

  • (nil)