Subprocess allows the creation of and interaction with child processes.
Processes can be communicated with using standard GIO-style APIs (ie: InputStream
, OutputStream). There are GIO-style APIs to wait for process termination
(ie: cancellable and with an asynchronous variant).
There is an API to force a process to terminate, as well as a race-free API for sending UNIX signals to a subprocess.
One major advantage that GIO brings over the core GLib library is comprehensive API for asynchronous I/O, such
splice_async. This makes GSubprocess significantly more powerful
and flexible than equivalent APIs in some other languages such as the `subprocess.py` included with Python. For example, using
Subprocess one could create two child processes, reading standard output from the first, processing it, and
writing to the input stream of the second, all without blocking the main loop.
A powerful communicate API is provided similar to the `communicate()`
method of `subprocess.py`. This enables very easy interaction with a subprocess that has been opened with pipes.
Subprocess defaults to tight control over the file descriptors open in the child process, avoiding dangling-fd
issues that are caused by a simple fork/exec(). The only open file descriptors in the spawned process are ones that were
explicitly specified by the Subprocess API (unless g_subprocess_flags_inherit_fds
was specified).
Subprocess will quickly reap all child processes as they exit, avoiding "zombie processes" remaining around
for long periods of time. wait can be used to wait for this to happen, but it will
happen even without the call being explicitly made.
As a matter of principle, Subprocess has no API that accepts shell-style space-separated strings. It will,
however, match the typical shell behaviour of searching the PATH for executables that do not contain a directory separator in their name.
By default, the `PATH` of the current process is used. You can specify g_subprocess_flags_search_path_from_envp
to use the `PATH` of the launcher environment instead.
Subprocess attempts to have a very simple API for most uses (ie: spawning a subprocess with arguments and
support for most typical kinds of input and output redirection). See
Subprocess. The SubprocessLauncher API is provided for more complicated
cases (advanced types of redirection, environment variable manipulation, change of working directory, child setup functions, etc).
A typical use of Subprocess will involve calling
Subprocess, followed by
wait_async or wait.
After the process exits, the status can be checked using functions such as
get_if_exited (which are similar to the familiar WIFEXITED-style POSIX macros).
- public bool communicate (Bytes? stdin_buf, Cancellable? cancellable, out Bytes? stdout_buf, out Bytes? stderr_buf) throws Error
Communicate with the subprocess until it terminates, and all input and
output has been completed.
- public async bool communicate_async (Bytes? stdin_buf, Cancellable? cancellable, out Bytes? stdout_buf, out Bytes? stderr_buf) throws Error
- public bool communicate_utf8 (string? stdin_buf, Cancellable? cancellable, out string? stdout_buf, out string? stderr_buf) throws Error
Like
communicate, but validates the output of the process as UTF-8, and returns it as a regular NUL terminated string.
- public async bool communicate_utf8_async (string? stdin_buf, Cancellable? cancellable, out string? stdout_buf, out string? stderr_buf) throws Error
- public void force_exit ()
Use an operating-system specific method to attempt an immediate,
forceful termination of the process.
- public int get_exit_status ()
Check the exit status of the subprocess, given that it exited
normally.
- public unowned string? get_identifier ()
On UNIX, returns the process ID as a decimal string.
- public bool get_if_exited ()
Check if the given subprocess exited normally (ie: by way of
exit or return from main).
- public bool get_if_signaled ()
Check if the given subprocess terminated in response to a signal.
- public int get_status ()
Gets the raw status code of the process, as from waitpid.
- public unowned InputStream? get_stderr_pipe ()
Gets the
InputStream from which to read the stderr output of this.
- public unowned OutputStream? get_stdin_pipe ()
Gets the
OutputStream that you can write to in order to give data to the stdin of this.
- public unowned InputStream? get_stdout_pipe ()
Gets the
InputStream from which to read the stdout output of this.
- public bool get_successful ()
Checks if the process was "successful".
- public int get_term_sig ()
Get the signal number that caused the subprocess to terminate, given
that it terminated due to a signal.
- public void send_signal (int signal_num)
Sends the UNIX signal signal_num to the subprocess, if it
is still running.
- public bool wait (Cancellable? cancellable = null) throws Error
Synchronously wait for the subprocess to terminate.
- public async bool wait_async (Cancellable? cancellable = null) throws Error
Wait for the subprocess to terminate.
- public bool wait_check (Cancellable? cancellable = null) throws Error
Combines wait
with check_wait_status.
- public async bool wait_check_async (Cancellable? cancellable = null) throws Error