Library
Module
Module type
Parameter
Class
Class type
Mini spawn library
Note: on Unix, spawn uses vfork by default. It has been tested, but if you believe this is causing a problem in your application, you can change this default at runtime by setting the environment variable SPAWN_USE_FORK
.
module Working_dir : sig ... end
module Unix_backend : sig ... end
module Env : sig ... end
module Pgid : sig ... end
Process group IDs
val spawn :
?env:Env.t ->
?cwd:Working_dir.t ->
prog:string ->
argv:string list ->
?stdin:Unix.file_descr ->
?stdout:Unix.file_descr ->
?stderr:Unix.file_descr ->
?unix_backend:Unix_backend.t ->
?setpgid:Pgid.t ->
unit ->
int
Spawn a sub-command and return its PID. This function is low-level and should be used to build higher-level APIs.
In case of errors, it raises Unix.Unix_error
.
Binary
prog
is not searched in PATH
. It is up to the caller to do the path resolution before calling this function. Note that there is no special treatment of executable text files without a proper #!. The execvp function from the C library calls /bin/sh
in this case to imitate the behaviors of a shell but this function doesn't.
Note that when prog
is a relative filename, it is interpreted as a path relative to the working directory specified by the cwd
argument. On Windows, this differs from what the underlying CreateProcess
function does.
Command line arguments
argv
is the full command line. The first element should be the program name and subsequent elements the command line arguments. Note that the head of argv
doesn't necessarily have to be equal to prog
. For instance it might be foo
while prog
might be /usr/bin/foo
.
Environment
env
represents the environment in which the sub-process is executed. If not specified, the environment from the process calling this function is used.
Working directory
cwd
describes what the current working directory of the sub-process should be. It defaults to Inherit
. It is an error to pass Fd _
on Windows.
Standard input/outputs
stdin
, stdout
and stderr
are the file descriptors used as standard input, output and error output of the sub-process. When not specified, they default to the ones from the calling process.
Process groups
If setpgid
is provided, the child will immediately call setpgid(0,pid)
, where pid
is a pid_t
determined from the Pgid.t
given (see that module). This parameter has no effect on Windows platforms.
Signals
On Unix, the sub-process will have all its signals unblocked.
Implementation
unix_backend
describes what backend to use on Unix. If set to Default
, vfork
is used unless the environment variable SPAWN_USE_FORK
is set. On Windows, CreateProcess
is used.