Module: Process

Defined in:
process.c

Overview

The Process module is a collection of methods used to manipulate processes.

Defined Under Namespace

Modules: GID, Sys, UID Classes: Status

Constant Summary collapse

WNOHANG = 
INT2FIX(0)
WUNTRACED = 
INT2FIX(0)
PRIO_PROCESS = 
INT2FIX(PRIO_PROCESS)
PRIO_PGRP = 
INT2FIX(PRIO_PGRP)
PRIO_USER = 
INT2FIX(PRIO_USER)
RLIM_SAVED_MAX = 
v
RLIM_INFINITY = 
inf
RLIM_SAVED_CUR = 
v
RLIMIT_CORE = 
INT2FIX(RLIMIT_CORE)
RLIMIT_CPU = 
INT2FIX(RLIMIT_CPU)
RLIMIT_DATA = 
INT2FIX(RLIMIT_DATA)
RLIMIT_FSIZE = 
INT2FIX(RLIMIT_FSIZE)
RLIMIT_NOFILE = 
INT2FIX(RLIMIT_NOFILE)
RLIMIT_STACK = 
INT2FIX(RLIMIT_STACK)
RLIMIT_AS = 
INT2FIX(RLIMIT_AS)
RLIMIT_MEMLOCK = 
INT2FIX(RLIMIT_MEMLOCK)
RLIMIT_NPROC = 
INT2FIX(RLIMIT_NPROC)
RLIMIT_RSS = 
INT2FIX(RLIMIT_RSS)
RLIMIT_SBSIZE = 
INT2FIX(RLIMIT_SBSIZE)

Class Method Summary collapse

Class Method Details

.abort ⇒ Object .Kernel::abort([msg]) ⇒ Object .Process::abort([msg]) ⇒ Object

Terminate execution immediately, effectively by calling Kernel.exit(false). If msg is given, it is written to STDERR prior to terminating.




# File 'process.c'

/*
 *  call-seq:
 *     abort
 *     Kernel::abort([msg])
 *     Process::abort([msg])
 *
 *  Terminate execution immediately, effectively by calling
 *  <code>Kernel.exit(false)</code>. If _msg_ is given, it is written
 *  to STDERR prior to terminating.
 */

VALUE
rb_f_abort(int argc, VALUE *argv)
{
    extern void ruby_error_print(void);

    rb_secure(4);
    if (argc == 0) {
    if (!NIL_P(GET_THREAD()->errinfo)) {
        ruby_error_print();
    }
    rb_exit(EXIT_FAILURE);
    }
    else {
    VALUE args[2];

    rb_scan_args(argc, argv, "1", &args[1]);
    StringValue(argv[0]);
    rb_io_puts(argc, argv, rb_stderr);
    args[0] = INT2NUM(EXIT_FAILURE);
    rb_exc_raise(rb_class_new_instance(2, args, rb_eSystemExit));
    }
    return Qnil;        /* not reached */
}

.daemon ⇒ 0 .daemon(nochdir = nil, noclose = nil) ⇒ 0

Detach the process from controlling terminal and run in the background as system daemon. Unless the argument nochdir is true (i.e. non false), it changes the current working directory to the root ("/"). Unless the argument noclose is true, daemon() will redirect standard input, standard output and standard error to /dev/null. Return zero on success, or raise one of Errno::*.

Overloads:

  • .daemon ⇒ 0

    Returns:

    • (0)
  • .daemon(nochdir = nil, noclose = nil) ⇒ 0

    Returns:

    • (0) 



# File 'process.c'

/*
 *  call-seq:
 *     Process.daemon()                        -> 0
 *     Process.daemon(nochdir=nil,noclose=nil) -> 0
 *
 *  Detach the process from controlling terminal and run in
 *  the background as system daemon.  Unless the argument
 *  nochdir is true (i.e. non false), it changes the current
 *  working directory to the root ("/"). Unless the argument
 *  noclose is true, daemon() will redirect standard input,
 *  standard output and standard error to /dev/null.
 *  Return zero on success, or raise one of Errno::*.
 */

static VALUE
proc_daemon(int argc, VALUE *argv)
{
    VALUE nochdir, noclose;
    int n;

    rb_secure(2);
    rb_scan_args(argc, argv, "02", &nochdir, &noclose);

#if defined(HAVE_DAEMON)
    prefork();
    before_fork();
    n = daemon(RTEST(nochdir), RTEST(noclose));
    after_fork();
    if (n < 0) rb_sys_fail("daemon");
    return INT2FIX(n);
#elif defined(HAVE_FORK)
    switch (rb_fork(0, 0, 0, Qnil)) {
      case -1:
    rb_sys_fail("daemon");
      case 0:
    break;
      default:
    _exit(EXIT_SUCCESS);
    }

    proc_setsid();

    /* must not be process-leader */
    switch (rb_fork(0, 0, 0, Qnil)) {
      case -1:
    rb_sys_fail("daemon");
      case 0:
    break;
      default:
    _exit(EXIT_SUCCESS);
    }

    if (!RTEST(nochdir))
    (void)chdir("/");

    if (!RTEST(noclose) && (n = open("/dev/null", O_RDWR, 0)) != -1) {
    (void)dup2(n, 0);
    (void)dup2(n, 1);
    (void)dup2(n, 2);
    if (n > 2)
        (void)close (n);
    }
    return INT2FIX(0);
#endif
}

.detach(pid) ⇒ Object

Some operating systems retain the status of terminated child processes until the parent collects that status (normally using some variant of wait(). If the parent never collects this status, the child stays around as a zombie process. Process::detach prevents this by setting up a separate Ruby thread whose sole job is to reap the status of the process pid when it terminates. Use detach only when you do not intent to explicitly wait for the child to terminate.

The waiting thread returns the exit status of the detached process when it terminates, so you can use Thread#join to know the result. If specified pid is not a valid child process ID, the thread returns nil immediately.

The waiting thread has pid method which returns the pid.

In this first example, we don't reap the first child process, so it appears as a zombie in the process status display.

p1 = fork { sleep 0.1 }
p2 = fork { sleep 0.2 }
Process.waitpid(p2)
sleep 2
system("ps -ho pid,state -p #{p1}")

produces:

27389 Z

In the next example, Process::detach is used to reap the child automatically.

p1 = fork { sleep 0.1 }
p2 = fork { sleep 0.2 }
Process.detach(p1)
Process.waitpid(p2)
sleep 2
system("ps -ho pid,state -p #{p1}")

(produces no output)




# File 'process.c'

/*
 *  call-seq:
 *     Process.detach(pid)   -> thread
 *
 *  Some operating systems retain the status of terminated child
 *  processes until the parent collects that status (normally using
 *  some variant of <code>wait()</code>. If the parent never collects
 *  this status, the child stays around as a <em>zombie</em> process.
 *  <code>Process::detach</code> prevents this by setting up a
 *  separate Ruby thread whose sole job is to reap the status of the
 *  process _pid_ when it terminates. Use <code>detach</code>
 *  only when you do not intent to explicitly wait for the child to
 *  terminate.
 *
 *  The waiting thread returns the exit status of the detached process
 *  when it terminates, so you can use <code>Thread#join</code> to
 *  know the result.  If specified _pid_ is not a valid child process
 *  ID, the thread returns +nil+ immediately.
 *
 *  The waiting thread has <code>pid</code> method which returns the pid.
 *
 *  In this first example, we don't reap the first child process, so
 *  it appears as a zombie in the process status display.
 *
 *     p1 = fork { sleep 0.1 }
 *     p2 = fork { sleep 0.2 }
 *     Process.waitpid(p2)
 *     sleep 2
 *     system("ps -ho pid,state -p #{p1}")
 *
 *  <em>produces:</em>
 *
 *     27389 Z
 *
 *  In the next example, <code>Process::detach</code> is used to reap
 *  the child automatically.
 *
 *     p1 = fork { sleep 0.1 }
 *     p2 = fork { sleep 0.2 }
 *     Process.detach(p1)
 *     Process.waitpid(p2)
 *     sleep 2
 *     system("ps -ho pid,state -p #{p1}")
 *
 *  <em>(produces no output)</em>
 */

static VALUE
proc_detach(VALUE obj, VALUE pid)
{
    rb_secure(2);
    return rb_detach_process(NUM2PIDT(pid));
}

.egid ⇒ Fixnum .Process::GID.eid ⇒ Fixnum .Process::Sys.geteid ⇒ Fixnum

Returns the effective group ID for this process. Not available on all platforms.

Process.egid   #=> 500

Overloads:




# File 'process.c'

/*
 *  call-seq:
 *     Process.egid          -> fixnum
 *     Process::GID.eid      -> fixnum
 *     Process::Sys.geteid   -> fixnum
 *
 *  Returns the effective group ID for this process. Not available on
 *  all platforms.
 *
 *     Process.egid   #=> 500
 */

static VALUE
proc_getegid(VALUE obj)
{
    rb_gid_t egid = getegid();

    return GIDT2NUM(egid);
}

.egid= ⇒ Object

.euid ⇒ Fixnum .Process::UID.eid ⇒ Fixnum .Process::Sys.geteuid ⇒ Fixnum

Returns the effective user ID for this process.

Process.euid   #=> 501

Overloads:




# File 'process.c'

/*
 *  call-seq:
 *     Process.euid           -> fixnum
 *     Process::UID.eid       -> fixnum
 *     Process::Sys.geteuid   -> fixnum
 *
 *  Returns the effective user ID for this process.
 *
 *     Process.euid   #=> 501
 */

static VALUE
proc_geteuid(VALUE obj)
{
    rb_uid_t euid = geteuid();
    return UIDT2NUM(euid);
}

.euid= ⇒ Object

.exec([env,][,options]) ⇒ Object

Replaces the current process by running the given external command. command... is one of following forms.

commandline                 : command line string which is passed to the standard shell
cmdname, arg1, ...          : command name and one or more arguments (no shell)
[cmdname, argv0], arg1, ... : command name, argv[0] and zero or more arguments (no shell)

If single string is given as the command, it is taken as a command line that is subject to shell expansion before being executed.

The standard shell means always "/bin/sh" on Unix-like systems, ENV["RUBYSHELL"] or ENV["COMSPEC"] on Windows NT series, and similar.

If two or more string given, the first is taken as a command name and the rest are passed as parameters to command with no shell expansion.

If a two-element array at the beginning of the command, the first element is the command to be executed, and the second argument is used as the argv[0] value, which may show up in process listings.

In order to execute the command, one of the exec(2) system calls is used, so the running command may inherit some of the environment of the original program (including open file descriptors). This behavior is modified by env and options. See spawn for details.

Raises SystemCallError if the command couldn't execute (typically Errno::ENOENT when it was not found).

exec "echo *"       # echoes list of files in current directory
# never get here

exec "echo", "*"    # echoes an asterisk
# never get here




# File 'process.c'

/*
 *  call-seq:
 *     exec([env,] command... [,options])
 *
 *  Replaces the current process by running the given external _command_.
 *  _command..._ is one of following forms.
 *
 *    commandline                 : command line string which is passed to the standard shell
 *    cmdname, arg1, ...          : command name and one or more arguments (no shell)
 *    [cmdname, argv0], arg1, ... : command name, argv[0] and zero or more arguments (no shell)
 *
 *  If single string is given as the command,
 *  it is taken as a command line that is subject to shell expansion before being executed.
 *
 *  The standard shell means always <code>"/bin/sh"</code> on Unix-like systems,
 *  <code>ENV["RUBYSHELL"]</code> or <code>ENV["COMSPEC"]</code> on Windows NT series, and
 *  similar.
 *
 *  If two or more +string+ given,
 *  the first is taken as a command name and
 *  the rest are passed as parameters to command with no shell expansion.
 *
 *  If a two-element array at the beginning of the command,
 *  the first element is the command to be executed,
 *  and the second argument is used as the <code>argv[0]</code> value,
 *  which may show up in process listings.
 *
 *  In order to execute the command, one of the <code>exec(2)</code>
 *  system calls is used, so the running command may inherit some of the environment
 *  of the original program (including open file descriptors).
 *  This behavior is modified by env and options.
 *  See <code>spawn</code> for details.
 *
 *  Raises SystemCallError if the command couldn't execute (typically
 *  <code>Errno::ENOENT</code> when it was not found).
 *
 *     exec "echo *"       # echoes list of files in current directory
 *     # never get here
 *
 *
 *     exec "echo", "*"    # echoes an asterisk
 *     # never get here
 */

VALUE
rb_f_exec(int argc, VALUE *argv)
{
    struct rb_exec_arg earg;
#define CHILD_ERRMSG_BUFLEN 80
    char errmsg[CHILD_ERRMSG_BUFLEN] = { '\0' };

    rb_exec_arg_init(argc, argv, TRUE, &earg);
    if (NIL_P(rb_ary_entry(earg.options, EXEC_OPTION_CLOSE_OTHERS)))
        rb_exec_arg_addopt(&earg, ID2SYM(rb_intern("close_others")), Qfalse);
    rb_exec_arg_fixup(&earg);

    rb_exec_err(&earg, errmsg, sizeof(errmsg));
    if (errmsg[0])
        rb_sys_fail(errmsg);
    rb_sys_fail(earg.prog);
    return Qnil;        /* dummy */
}

.exit(status = true) ⇒ Object .Kernel::exit(status = true) ⇒ Object .Process::exit(status = true) ⇒ Object

Initiates the termination of the Ruby script by raising the SystemExit exception. This exception may be caught. The optional parameter is used to return a status code to the invoking environment. true and FALSE of status means success and failure respectively. The interpretation of other integer values are system dependent.

begin
  exit
  puts "never get here"
rescue SystemExit
  puts "rescued a SystemExit exception"
end
puts "after begin block"

produces:

rescued a SystemExit exception
after begin block

Just prior to termination, Ruby executes any at_exit functions (see Kernel::at_exit) and runs any object finalizers (see ObjectSpace::define_finalizer).

at_exit { puts "at_exit function" }
ObjectSpace.define_finalizer("string",  proc { puts "in finalizer" })
exit

produces:

at_exit function
in finalizer




# File 'process.c'

/*
 *  call-seq:
 *     exit(status=true)
 *     Kernel::exit(status=true)
 *     Process::exit(status=true)
 *
 *  Initiates the termination of the Ruby script by raising the
 *  <code>SystemExit</code> exception. This exception may be caught. The
 *  optional parameter is used to return a status code to the invoking
 *  environment.
 *  +true+ and +FALSE+ of _status_ means success and failure
 *  respectively.  The interpretation of other integer values are
 *  system dependent.
 *
 *     begin
 *       exit
 *       puts "never get here"
 *     rescue SystemExit
 *       puts "rescued a SystemExit exception"
 *     end
 *     puts "after begin block"
 *
 *  <em>produces:</em>
 *
 *     rescued a SystemExit exception
 *     after begin block
 *
 *  Just prior to termination, Ruby executes any <code>at_exit</code> functions
 *  (see Kernel::at_exit) and runs any object finalizers (see
 *  ObjectSpace::define_finalizer).
 *
 *     at_exit { puts "at_exit function" }
 *     ObjectSpace.define_finalizer("string",  proc { puts "in finalizer" })
 *     exit
 *
 *  <em>produces:</em>
 *
 *     at_exit function
 *     in finalizer
 */

VALUE
rb_f_exit(int argc, VALUE *argv)
{
    VALUE status;
    int istatus;

    rb_secure(4);
    if (argc > 0 && rb_scan_args(argc, argv, "01", &status) == 1) {
    switch (status) {
      case Qtrue:
        istatus = EXIT_SUCCESS;
        break;
      case Qfalse:
        istatus = EXIT_FAILURE;
        break;
      default:
        istatus = NUM2INT(status);
#if EXIT_SUCCESS != 0
        if (istatus == 0)
        istatus = EXIT_SUCCESS;
#endif
        break;
    }
    }
    else {
    istatus = EXIT_SUCCESS;
    }
    rb_exit(istatus);
    return Qnil;        /* not reached */
}

.exit!(status = false) ⇒ Object

Exits the process immediately. No exit handlers are run. status is returned to the underlying system as the exit status.

Process.exit!(true)




# File 'process.c'

/*
 *  call-seq:
 *     Process.exit!(status=false)
 *
 *  Exits the process immediately. No exit handlers are
 *  run. <em>status</em> is returned to the underlying system as the
 *  exit status.
 *
 *     Process.exit!(true)
 */

static VALUE
rb_f_exit_bang(int argc, VALUE *argv, VALUE obj)
{
    VALUE status;
    int istatus;

    rb_secure(4);
    if (argc > 0 && rb_scan_args(argc, argv, "01", &status) == 1) {
    switch (status) {
      case Qtrue:
        istatus = EXIT_SUCCESS;
        break;
      case Qfalse:
        istatus = EXIT_FAILURE;
        break;
      default:
        istatus = NUM2INT(status);
        break;
    }
    }
    else {
    istatus = EXIT_FAILURE;
    }
    _exit(istatus);

    return Qnil;        /* not reached */
}

.fork { ... } ⇒ Fixnum? .fork { ... } ⇒ Fixnum?

Creates a subprocess. If a block is specified, that block is run in the subprocess, and the subprocess terminates with a status of zero. Otherwise, the fork call returns twice, once in the parent, returning the process ID of the child, and once in the child, returning nil. The child process can exit using Kernel.exit! to avoid running any at_exit functions. The parent process should use Process.wait to collect the termination statuses of its children or use Process.detach to register disinterest in their status; otherwise, the operating system may accumulate zombie processes.

The thread calling fork is the only thread in the created child process. fork doesn't copy other threads.

If fork is not usable, Process.respond_to?(:fork) returns false.

Overloads:




# File 'process.c'

/*
 *  call-seq:
 *     Kernel.fork  [{ block }]   -> fixnum or nil
 *     Process.fork [{ block }]   -> fixnum or nil
 *
 *  Creates a subprocess. If a block is specified, that block is run
 *  in the subprocess, and the subprocess terminates with a status of
 *  zero. Otherwise, the +fork+ call returns twice, once in
 *  the parent, returning the process ID of the child, and once in
 *  the child, returning _nil_. The child process can exit using
 *  <code>Kernel.exit!</code> to avoid running any
 *  <code>at_exit</code> functions. The parent process should
 *  use <code>Process.wait</code> to collect the termination statuses
 *  of its children or use <code>Process.detach</code> to register
 *  disinterest in their status; otherwise, the operating system
 *  may accumulate zombie processes.
 *
 *  The thread calling fork is the only thread in the created child process.
 *  fork doesn't copy other threads.
 *
 *  If fork is not usable, Process.respond_to?(:fork) returns false.
 */

static VALUE
rb_f_fork(VALUE obj)
{
    rb_pid_t pid;

    rb_secure(2);

    switch (pid = rb_fork(0, 0, 0, Qnil)) {
      case 0:
    rb_thread_atfork();
    if (rb_block_given_p()) {
        int status;

        rb_protect(rb_yield, Qundef, &status);
        ruby_stop(status);
    }
    return Qnil;

      case -1:
    rb_sys_fail("fork(2)");
    return Qnil;

      default:
    return PIDT2NUM(pid);
    }
}

.getpgid(pid) ⇒ Integer

Returns the process group ID for the given process id. Not available on all platforms.

Process.getpgid(Process.ppid())   #=> 25527

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.getpgid(pid)   -> integer
 *
 *  Returns the process group ID for the given process id. Not
 *  available on all platforms.
 *
 *     Process.getpgid(Process.ppid())   #=> 25527
 */

static VALUE
proc_getpgid(VALUE obj, VALUE pid)
{
    rb_pid_t i;

    rb_secure(2);
    i = getpgid(NUM2PIDT(pid));
    if (i < 0) rb_sys_fail(0);
    return PIDT2NUM(i);
}

.getpgrp ⇒ Integer

Returns the process group ID for this process. Not available on all platforms.

Process.getpgid(0)   #=> 25527
Process.getpgrp      #=> 25527

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.getpgrp   -> integer
 *
 *  Returns the process group ID for this process. Not available on
 *  all platforms.
 *
 *     Process.getpgid(0)   #=> 25527
 *     Process.getpgrp      #=> 25527
 */

static VALUE
proc_getpgrp(void)
{
    rb_pid_t pgrp;

    rb_secure(2);
#if defined(HAVE_GETPGRP) && defined(GETPGRP_VOID)
    pgrp = getpgrp();
    if (pgrp < 0) rb_sys_fail(0);
    return PIDT2NUM(pgrp);
#else /* defined(HAVE_GETPGID) */
    pgrp = getpgid(0);
    if (pgrp < 0) rb_sys_fail(0);
    return PIDT2NUM(pgrp);
#endif
}

.getpriority(kind, integer) ⇒ Fixnum

Gets the scheduling priority for specified process, process group, or user. kind indicates the kind of entity to find: one of Process::PRIO_PGRP, Process::PRIO_USER, or Process::PRIO_PROCESS. integer is an id indicating the particular process, process group, or user (an id of 0 means current). Lower priorities are more favorable for scheduling. Not available on all platforms.

Process.getpriority(Process::PRIO_USER, 0)      #=> 19
Process.getpriority(Process::PRIO_PROCESS, 0)   #=> 19

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.getpriority(kind, integer)   -> fixnum
 *
 *  Gets the scheduling priority for specified process, process group,
 *  or user. <em>kind</em> indicates the kind of entity to find: one
 *  of <code>Process::PRIO_PGRP</code>,
 *  <code>Process::PRIO_USER</code>, or
 *  <code>Process::PRIO_PROCESS</code>. _integer_ is an id
 *  indicating the particular process, process group, or user (an id
 *  of 0 means _current_). Lower priorities are more favorable
 *  for scheduling. Not available on all platforms.
 *
 *     Process.getpriority(Process::PRIO_USER, 0)      #=> 19
 *     Process.getpriority(Process::PRIO_PROCESS, 0)   #=> 19
 */

static VALUE
proc_getpriority(VALUE obj, VALUE which, VALUE who)
{
    int prio, iwhich, iwho;

    rb_secure(2);
    iwhich = NUM2INT(which);
    iwho   = NUM2INT(who);

    errno = 0;
    prio = getpriority(iwhich, iwho);
    if (errno) rb_sys_fail(0);
    return INT2FIX(prio);
}

.getrlimit(resource) ⇒ Array

Gets the resource limit of the process. cur_limit means current (soft) limit and max_limit means maximum (hard) limit.

resource indicates the kind of resource to limit. It is specified as a symbol such as :CORE, a string such as "CORE" or a constant such as Process::RLIMIT_CORE. See Process.setrlimit for details.

cur_limit and max_limit may be Process::RLIM_INFINITY, Process::RLIM_SAVED_MAX or Process::RLIM_SAVED_CUR. See Process.setrlimit and the system getrlimit(2) manual for details.

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.getrlimit(resource)   -> [cur_limit, max_limit]
 *
 *  Gets the resource limit of the process.
 *  _cur_limit_ means current (soft) limit and
 *  _max_limit_ means maximum (hard) limit.
 *
 *  _resource_ indicates the kind of resource to limit.
 *  It is specified as a symbol such as <code>:CORE</code>,
 *  a string such as <code>"CORE"</code> or
 *  a constant such as <code>Process::RLIMIT_CORE</code>.
 *  See Process.setrlimit for details.
 *
 *  _cur_limit_ and _max_limit_ may be <code>Process::RLIM_INFINITY</code>,
 *  <code>Process::RLIM_SAVED_MAX</code> or
 *  <code>Process::RLIM_SAVED_CUR</code>.
 *  See Process.setrlimit and the system getrlimit(2) manual for details.
 */

static VALUE
proc_getrlimit(VALUE obj, VALUE resource)
{
    struct rlimit rlim;

    rb_secure(2);

    if (getrlimit(rlimit_resource_type(resource), &rlim) < 0) {
    rb_sys_fail("getrlimit");
    }
    return rb_assoc_new(RLIM2NUM(rlim.rlim_cur), RLIM2NUM(rlim.rlim_max));
}

.gid ⇒ Fixnum .Process::GID.rid ⇒ Fixnum .Process::Sys.getgid ⇒ Fixnum

Returns the (real) group ID for this process.

Process.gid   #=> 500

Overloads:




# File 'process.c'

/*
 *  call-seq:
 *     Process.gid           -> fixnum
 *     Process::GID.rid      -> fixnum
 *     Process::Sys.getgid   -> fixnum
 *
 *  Returns the (real) group ID for this process.
 *
 *     Process.gid   #=> 500
 */

static VALUE
proc_getgid(VALUE obj)
{
    rb_gid_t gid = getgid();
    return GIDT2NUM(gid);
}

.gid=(fixnum) ⇒ Fixnum

Sets the group ID for this process.

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.gid= fixnum   -> fixnum
 *
 *  Sets the group ID for this process.
 */

static VALUE
proc_setgid(VALUE obj, VALUE id)
{
    rb_gid_t gid;

    check_gid_switch();

    gid = NUM2GIDT(id);
#if defined(HAVE_SETRESGID)
    if (setresgid(gid, -1, -1) < 0) rb_sys_fail(0);
#elif defined HAVE_SETREGID
    if (setregid(gid, -1) < 0) rb_sys_fail(0);
#elif defined HAVE_SETRGID
    if (setrgid(gid) < 0) rb_sys_fail(0);
#elif defined HAVE_SETGID
    {
    if (getegid() == gid) {
        if (setgid(gid) < 0) rb_sys_fail(0);
    }
    else {
        rb_notimplement();
    }
    }
#endif
    return GIDT2NUM(gid);
}

.groups ⇒ Array

Get an Array of the gids of groups in the supplemental group access list for this process.

Process.groups   #=> [27, 6, 10, 11]

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.groups   -> array
 *
 *  Get an <code>Array</code> of the gids of groups in the
 *  supplemental group access list for this process.
 *
 *     Process.groups   #=> [27, 6, 10, 11]
 *
 */

static VALUE
proc_getgroups(VALUE obj)
{
    VALUE ary;
    int i, ngroups;
    rb_gid_t *groups;

    groups = ALLOCA_N(rb_gid_t, maxgroups);

    ngroups = getgroups(maxgroups, groups);
    if (ngroups == -1)
    rb_sys_fail(0);

    ary = rb_ary_new();
    for (i = 0; i < ngroups; i++)
    rb_ary_push(ary, GIDT2NUM(groups[i]));

    return ary;
}

.groups=(array) ⇒ Array

Set the supplemental group access list to the given Array of group IDs.

Process.groups   #=> [0, 1, 2, 3, 4, 6, 10, 11, 20, 26, 27]
Process.groups = [27, 6, 10, 11]   #=> [27, 6, 10, 11]
Process.groups   #=> [27, 6, 10, 11]

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.groups= array   -> array
 *
 *  Set the supplemental group access list to the given
 *  <code>Array</code> of group IDs.
 *
 *     Process.groups   #=> [0, 1, 2, 3, 4, 6, 10, 11, 20, 26, 27]
 *     Process.groups = [27, 6, 10, 11]   #=> [27, 6, 10, 11]
 *     Process.groups   #=> [27, 6, 10, 11]
 *
 */

static VALUE
proc_setgroups(VALUE obj, VALUE ary)
{
    size_t ngroups, i;
    rb_gid_t *groups;
    struct group *gr;

    Check_Type(ary, T_ARRAY);

    ngroups = RARRAY_LEN(ary);
    if (ngroups > (size_t)maxgroups)
    rb_raise(rb_eArgError, "too many groups, %u max", maxgroups);

    groups = ALLOCA_N(rb_gid_t, ngroups);

    for (i = 0; i < ngroups && i < (size_t)RARRAY_LEN(ary); i++) {
    VALUE g = RARRAY_PTR(ary)[i];

    if (FIXNUM_P(g)) {
        groups[i] = NUM2GIDT(g);
    }
    else {
        VALUE tmp = rb_check_string_type(g);

        if (NIL_P(tmp)) {
        groups[i] = NUM2GIDT(g);
        }
        else {
        gr = getgrnam(RSTRING_PTR(tmp));
        if (gr == NULL)
            rb_raise(rb_eArgError,
                 "can't find group for %s", RSTRING_PTR(tmp));
        groups[i] = gr->gr_gid;
        }
    }
    }

    if (setgroups((int)ngroups, groups) == -1) /* ngroups <= maxgroups */
    rb_sys_fail(0);

    return proc_getgroups(obj);
}

.initgroups(username, gid) ⇒ Array

Initializes the supplemental group access list by reading the system group database and using all groups of which the given user is a member. The group with the specified gid is also added to the list. Returns the resulting Array of the gids of all the groups in the supplementary group access list. Not available on all platforms.

Process.groups   #=> [0, 1, 2, 3, 4, 6, 10, 11, 20, 26, 27]
Process.initgroups( "mgranger", 30 )   #=> [30, 6, 10, 11]
Process.groups   #=> [30, 6, 10, 11]

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.initgroups(username, gid)   -> array
 *
 *  Initializes the supplemental group access list by reading the
 *  system group database and using all groups of which the given user
 *  is a member. The group with the specified <em>gid</em> is also
 *  added to the list. Returns the resulting <code>Array</code> of the
 *  gids of all the groups in the supplementary group access list. Not
 *  available on all platforms.
 *
 *     Process.groups   #=> [0, 1, 2, 3, 4, 6, 10, 11, 20, 26, 27]
 *     Process.initgroups( "mgranger", 30 )   #=> [30, 6, 10, 11]
 *     Process.groups   #=> [30, 6, 10, 11]
 *
 */

static VALUE
proc_initgroups(VALUE obj, VALUE uname, VALUE base_grp)
{
    if (initgroups(StringValuePtr(uname), NUM2GIDT(base_grp)) != 0) {
    rb_sys_fail(0);
    }
    return proc_getgroups(obj);
}

.kill(signal, pid, ...) ⇒ Fixnum

Sends the given signal to the specified process id(s), or to the current process if pid is zero. signal may be an integer signal number or a POSIX signal name (either with or without a SIG prefix). If signal is negative (or starts with a minus sign), kills process groups instead of processes. Not all signals are available on all platforms.

pid = fork do
   Signal.trap("HUP") { puts "Ouch!"; exit }
   # ... do some work ...
end
# ...
Process.kill("HUP", pid)
Process.wait

produces:

Ouch!

If signal is an integer but wrong for signal, Errno::EINVAL or RangeError will be raised. Otherwise unless signal is a String or a Symbol, and a known signal name, ArgumentError will be raised.

Also, Errno::ESRCH or RangeError for invalid pid, Errno::EPERM when failed because of no privilege, will be raised. In these cases, signals may have been sent to preceding processes.

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.kill(signal, pid, ...)    -> fixnum
 *
 *  Sends the given signal to the specified process id(s), or to the
 *  current process if _pid_ is zero. _signal_ may be an
 *  integer signal number or a POSIX signal name (either with or without
 *  a +SIG+ prefix). If _signal_ is negative (or starts
 *  with a minus sign), kills process groups instead of
 *  processes. Not all signals are available on all platforms.
 *
 *     pid = fork do
 *        Signal.trap("HUP") { puts "Ouch!"; exit }
 *        # ... do some work ...
 *     end
 *     # ...
 *     Process.kill("HUP", pid)
 *     Process.wait
 *
 *  <em>produces:</em>
 *
 *     Ouch!
 *
 *  If _signal_ is an integer but wrong for signal,
 *  <code>Errno::EINVAL</code> or +RangeError+ will be raised.
 *  Otherwise unless _signal_ is a +String+ or a +Symbol+, and a known
 *  signal name, +ArgumentError+ will be raised.
 *
 *  Also, <code>Errno::ESRCH</code> or +RangeError+ for invalid _pid_,
 *  <code>Errno::EPERM</code> when failed because of no privilege,
 *  will be raised.  In these cases, signals may have been sent to
 *  preceding processes.
 */

VALUE
rb_f_kill(int argc, VALUE *argv)
{
#ifndef HAS_KILLPG
#define killpg(pg, sig) kill(-(pg), sig)
#endif
    int negative = 0;
    int sig;
    int i;
    const char *s;

    rb_secure(2);
    if (argc < 2)
	rb_raise(rb_eArgError, "wrong number of arguments (%d for at least 2)", argc);
    switch (TYPE(argv[0])) {
      case T_FIXNUM:
	sig = FIX2INT(argv[0]);
	break;

      case T_SYMBOL:
	s = rb_id2name(SYM2ID(argv[0]));
	if (!s) rb_raise(rb_eArgError, "bad signal");
	goto str_signal;

      case T_STRING:
	s = RSTRING_PTR(argv[0]);
	if (s[0] == '-') {
	    negative++;
	    s++;
	}
      str_signal:
	if (strncmp("SIG", s, 3) == 0)
	    s += 3;
	if((sig = signm2signo(s)) == 0)
	    rb_raise(rb_eArgError, "unsupported name `SIG%s'", s);

	if (negative)
	    sig = -sig;
	break;

      default:
        {
	    VALUE str;

	    str = rb_check_string_type(argv[0]);
	    if (!NIL_P(str)) {
		s = RSTRING_PTR(str);
		goto str_signal;
	    }
	    rb_raise(rb_eArgError, "bad signal type %s",
		     rb_obj_classname(argv[0]));
	}
	break;
    }

    if (sig < 0) {
	sig = -sig;
	for (i=1; i<argc; i++) {
	    if (killpg(NUM2PIDT(argv[i]), sig) < 0)
		rb_sys_fail(0);
	}
    }
    else {
	for (i=1; i<argc; i++) {
	    if (kill(NUM2PIDT(argv[i]), sig) < 0)
		rb_sys_fail(0);
	}
    }
    rb_thread_polling();
    return INT2FIX(i-1);
}

.maxgroups ⇒ Fixnum

Returns the maximum number of gids allowed in the supplemental group access list.

Process.maxgroups   #=> 32

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.maxgroups   -> fixnum
 *
 *  Returns the maximum number of gids allowed in the supplemental
 *  group access list.
 *
 *     Process.maxgroups   #=> 32
 */

static VALUE
proc_getmaxgroups(VALUE obj)
{
    return INT2FIX(maxgroups);
}

.maxgroups=(fixnum) ⇒ Fixnum

Sets the maximum number of gids allowed in the supplemental group access list.

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.maxgroups= fixnum   -> fixnum
 *
 *  Sets the maximum number of gids allowed in the supplemental group
 *  access list.
 */

static VALUE
proc_setmaxgroups(VALUE obj, VALUE val)
{
    int ngroups = FIX2UINT(val);

    if (ngroups > 4096)
    ngroups = 4096;

    maxgroups = ngroups;

    return INT2FIX(maxgroups);
}

.pid ⇒ Fixnum

Returns the process id of this process. Not available on all platforms.

Process.pid   #=> 27415

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.pid   -> fixnum
 *
 *  Returns the process id of this process. Not available on all
 *  platforms.
 *
 *     Process.pid   #=> 27415
 */

static VALUE
get_pid(void)
{
    rb_secure(2);
    return PIDT2NUM(getpid());
}

.ppid ⇒ Fixnum

Returns the process id of the parent of this process. Returns untrustworthy value on Win32/64. Not available on all platforms.

puts "I am #{Process.pid}"
Process.fork { puts "Dad is #{Process.ppid}" }

produces:

I am 27417
Dad is 27417

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.ppid   -> fixnum
 *
 *  Returns the process id of the parent of this process. Returns
 *  untrustworthy value on Win32/64. Not available on all platforms.
 *
 *     puts "I am #{Process.pid}"
 *     Process.fork { puts "Dad is #{Process.ppid}" }
 *
 *  <em>produces:</em>
 *
 *     I am 27417
 *     Dad is 27417
 */

static VALUE
get_ppid(void)
{
    rb_secure(2);
    return PIDT2NUM(getppid());
}

.setpgid(pid, integer) ⇒ 0

Sets the process group ID of pid (0 indicates this process) to integer. Not available on all platforms.

Returns:

  • (0) 



# File 'process.c'

/*
 *  call-seq:
 *     Process.setpgid(pid, integer)   -> 0
 *
 *  Sets the process group ID of _pid_ (0 indicates this
 *  process) to <em>integer</em>. Not available on all platforms.
 */

static VALUE
proc_setpgid(VALUE obj, VALUE pid, VALUE pgrp)
{
    rb_pid_t ipid, ipgrp;

    rb_secure(2);
    ipid = NUM2PIDT(pid);
    ipgrp = NUM2PIDT(pgrp);

    if (setpgid(ipid, ipgrp) < 0) rb_sys_fail(0);
    return INT2FIX(0);
}

.setpgrp ⇒ 0

Equivalent to setpgid(0,0). Not available on all platforms.

Returns:

  • (0) 



# File 'process.c'

/*
 *  call-seq:
 *     Process.setpgrp   -> 0
 *
 *  Equivalent to <code>setpgid(0,0)</code>. Not available on all
 *  platforms.
 */

static VALUE
proc_setpgrp(void)
{
    rb_secure(2);
  /* check for posix setpgid() first; this matches the posix */
  /* getpgrp() above.  It appears that configure will set SETPGRP_VOID */
  /* even though setpgrp(0,0) would be preferred. The posix call avoids */
  /* this confusion. */
#ifdef HAVE_SETPGID
    if (setpgid(0,0) < 0) rb_sys_fail(0);
#elif defined(HAVE_SETPGRP) && defined(SETPGRP_VOID)
    if (setpgrp() < 0) rb_sys_fail(0);
#endif
    return INT2FIX(0);
}

.setpriority(kind, integer, priority) ⇒ 0

See Process#getpriority.

Process.setpriority(Process::PRIO_USER, 0, 19)      #=> 0
Process.setpriority(Process::PRIO_PROCESS, 0, 19)   #=> 0
Process.getpriority(Process::PRIO_USER, 0)          #=> 19
Process.getpriority(Process::PRIO_PROCESS, 0)       #=> 19

Returns:

  • (0) 



# File 'process.c'

/*
 *  call-seq:
 *     Process.setpriority(kind, integer, priority)   -> 0
 *
 *  See <code>Process#getpriority</code>.
 *
 *     Process.setpriority(Process::PRIO_USER, 0, 19)      #=> 0
 *     Process.setpriority(Process::PRIO_PROCESS, 0, 19)   #=> 0
 *     Process.getpriority(Process::PRIO_USER, 0)          #=> 19
 *     Process.getpriority(Process::PRIO_PROCESS, 0)       #=> 19
 */

static VALUE
proc_setpriority(VALUE obj, VALUE which, VALUE who, VALUE prio)
{
    int iwhich, iwho, iprio;

    rb_secure(2);
    iwhich = NUM2INT(which);
    iwho   = NUM2INT(who);
    iprio  = NUM2INT(prio);

    if (setpriority(iwhich, iwho, iprio) < 0)
    rb_sys_fail(0);
    return INT2FIX(0);
}

.setrlimit(resource, cur_limit, max_limit) ⇒ nil .setrlimit(resource, cur_limit) ⇒ nil

Sets the resource limit of the process. cur_limit means current (soft) limit and max_limit means maximum (hard) limit.

If max_limit is not given, cur_limit is used.

resource indicates the kind of resource to limit. It should be a symbol such as :CORE, a string such as "CORE" or a constant such as Process::RLIMIT_CORE. The available resources are OS dependent. Ruby may support following resources.

CORE

core size (bytes) (SUSv3)

CPU

CPU time (seconds) (SUSv3)

DATA

data segment (bytes) (SUSv3)

FSIZE

file size (bytes) (SUSv3)

NOFILE

file descriptors (number) (SUSv3)

STACK

stack size (bytes) (SUSv3)

AS

total available memory (bytes) (SUSv3, NetBSD, FreeBSD, OpenBSD but 4.4BSD-Lite)

MEMLOCK

total size for mlock(2) (bytes) (4.4BSD, GNU/Linux)

NPROC

number of processes for the user (number) (4.4BSD, GNU/Linux)

RSS

resident memory size (bytes) (4.2BSD, GNU/Linux)

SBSIZE

all socket buffers (bytes) (NetBSD, FreeBSD)

cur_limit and max_limit may be :INFINITY, "INFINITY" or Process::RLIM_INFINITY, which means that the resource is not limited. They may be Process::RLIM_SAVED_MAX, Process::RLIM_SAVED_CUR and corresponding symbols and strings too. See system setrlimit(2) manual for details.

The following example raise the soft limit of core size to the hard limit to try to make core dump possible.

Process.setrlimit(:CORE, Process.getrlimit(:CORE)[1])

Overloads:

  • .setrlimit(resource, cur_limit, max_limit) ⇒ nil

    Returns:

    • (nil)
  • .setrlimit(resource, cur_limit) ⇒ nil

    Returns:

    • (nil) 



# File 'process.c'

/*
 *  call-seq:
 *     Process.setrlimit(resource, cur_limit, max_limit)        -> nil
 *     Process.setrlimit(resource, cur_limit)                   -> nil
 *
 *  Sets the resource limit of the process.
 *  _cur_limit_ means current (soft) limit and
 *  _max_limit_ means maximum (hard) limit.
 *
 *  If _max_limit_ is not given, _cur_limit_ is used.
 *
 *  _resource_ indicates the kind of resource to limit.
 *  It should be a symbol such as <code>:CORE</code>,
 *  a string such as <code>"CORE"</code> or
 *  a constant such as <code>Process::RLIMIT_CORE</code>.
 *  The available resources are OS dependent.
 *  Ruby may support following resources.
 *
 *  [CORE] core size (bytes) (SUSv3)
 *  [CPU] CPU time (seconds) (SUSv3)
 *  [DATA] data segment (bytes) (SUSv3)
 *  [FSIZE] file size (bytes) (SUSv3)
 *  [NOFILE] file descriptors (number) (SUSv3)
 *  [STACK] stack size (bytes) (SUSv3)
 *  [AS] total available memory (bytes) (SUSv3, NetBSD, FreeBSD, OpenBSD but 4.4BSD-Lite)
 *  [MEMLOCK] total size for mlock(2) (bytes) (4.4BSD, GNU/Linux)
 *  [NPROC] number of processes for the user (number) (4.4BSD, GNU/Linux)
 *  [RSS] resident memory size (bytes) (4.2BSD, GNU/Linux)
 *  [SBSIZE] all socket buffers (bytes) (NetBSD, FreeBSD)
 *
 *  _cur_limit_ and _max_limit_ may be
 *  <code>:INFINITY</code>, <code>"INFINITY"</code> or
 *  <code>Process::RLIM_INFINITY</code>,
 *  which means that the resource is not limited.
 *  They may be <code>Process::RLIM_SAVED_MAX</code>,
 *  <code>Process::RLIM_SAVED_CUR</code> and
 *  corresponding symbols and strings too.
 *  See system setrlimit(2) manual for details.
 *
 *  The following example raise the soft limit of core size to
 *  the hard limit to try to make core dump possible.
 *
 *    Process.setrlimit(:CORE, Process.getrlimit(:CORE)[1])
 *
 */

static VALUE
proc_setrlimit(int argc, VALUE *argv, VALUE obj)
{
    VALUE resource, rlim_cur, rlim_max;
    struct rlimit rlim;

    rb_secure(2);

    rb_scan_args(argc, argv, "21", &resource, &rlim_cur, &rlim_max);
    if (rlim_max == Qnil)
        rlim_max = rlim_cur;

    rlim.rlim_cur = rlimit_resource_value(rlim_cur);
    rlim.rlim_max = rlimit_resource_value(rlim_max);

    if (setrlimit(rlimit_resource_type(resource), &rlim) < 0) {
    rb_sys_fail("setrlimit");
    }
    return Qnil;
}

.setsid ⇒ Fixnum

Establishes this process as a new session and process group leader, with no controlling tty. Returns the session id. Not available on all platforms.

Process.setsid   #=> 27422

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.setsid   -> fixnum
 *
 *  Establishes this process as a new session and process group
 *  leader, with no controlling tty. Returns the session id. Not
 *  available on all platforms.
 *
 *     Process.setsid   #=> 27422
 */

static VALUE
proc_setsid(void)
{
    rb_pid_t pid;

    rb_secure(2);
    pid = setsid();
    if (pid < 0) rb_sys_fail(0);
    return PIDT2NUM(pid);
}

.spawn([env,][,options]) ⇒ Object .spawn([env,][,options]) ⇒ Object

spawn executes specified command and return its pid.

This method doesn't wait for end of the command. The parent process should use Process.wait to collect the termination status of its child or use Process.detach to register disinterest in their status; otherwise, the operating system may accumulate zombie processes.

spawn has bunch of options to specify process attributes:

env: hash
  name => val : set the environment variable
  name => nil : unset the environment variable
command...:
  commandline                 : command line string which is passed to the standard shell
  cmdname, arg1, ...          : command name and one or more arguments (no shell)
  [cmdname, argv0], arg1, ... : command name, argv[0] and zero or more arguments (no shell)
options: hash
  clearing environment variables:
    :unsetenv_others => true   : clear environment variables except specified by env
    :unsetenv_others => false  : don't clear (default)
  process group:
    :pgroup => true or 0 : make a new process group
    :pgroup => pgid      : join to specified process group
    :pgroup => nil       : don't change the process group (default)
  resource limit: resourcename is core, cpu, data, etc.  See Process.setrlimit.
    :rlimit_resourcename => limit
    :rlimit_resourcename => [cur_limit, max_limit]
  current directory:
    :chdir => str
  umask:
    :umask => int
  redirection:
    key:
      FD              : single file descriptor in child process
      [FD, FD, ...]   : multiple file descriptor in child process
    value:
      FD                        : redirect to the file descriptor in parent process
      string                    : redirect to file with open(string, "r" or "w")
      [string]                  : redirect to file with open(string, File::RDONLY)
      [string, open_mode]       : redirect to file with open(string, open_mode, 0644)
      [string, open_mode, perm] : redirect to file with open(string, open_mode, perm)
      [:child, FD]              : redirect to the redirected file descriptor
      :close                    : close the file descriptor in child process
    FD is one of follows
      :in     : the file descriptor 0 which is the standard input
      :out    : the file descriptor 1 which is the standard output
      :err    : the file descriptor 2 which is the standard error
      integer : the file descriptor of specified the integer
      io      : the file descriptor specified as io.fileno
  file descriptor inheritance: close non-redirected non-standard fds (3, 4, 5, ...) or not
    :close_others => false : inherit fds (default for system and exec)
    :close_others => true  : don't inherit (default for spawn and IO.popen)

If a hash is given as env, the environment is updated by env before exec(2) in the child process. If a pair in env has nil as the value, the variable is deleted.

# set FOO as BAR and unset BAZ.
pid = spawn({"FOO"=>"BAR", "BAZ"=>nil}, command)

If a hash is given as options, it specifies process group, resource limit, current directory, umask and redirects for the child process. Also, it can be specified to clear environment variables.

The :unsetenv_others key in options specifies to clear environment variables, other than specified by env.

pid = spawn(command, :unsetenv_others=>true) # no environment variable
pid = spawn({"FOO"=>"BAR"}, command, :unsetenv_others=>true) # FOO only

The :pgroup key in options specifies a process group. The corresponding value should be true, zero or positive integer. true and zero means the process should be a process leader of a new process group. Other values specifies a process group to be belongs.

pid = spawn(command, :pgroup=>true) # process leader
pid = spawn(command, :pgroup=>10) # belongs to the process group 10

The :rlimit_foo key specifies a resource limit. foo should be one of resource types such as core. The corresponding value should be an integer or an array which have one or two integers: same as cur_limit and max_limit arguments for Process.setrlimit.

cur, max = Process.getrlimit(:CORE)
pid = spawn(command, :rlimit_core=>[0,max]) # disable core temporary.
pid = spawn(command, :rlimit_core=>max) # enable core dump
pid = spawn(command, :rlimit_core=>0) # never dump core.

The :chdir key in options specifies the current directory.

pid = spawn(command, :chdir=>"/var/tmp")

The :umask key in options specifies the umask.

pid = spawn(command, :umask=>077)

The :in, :out, :err, a fixnum, an IO and an array key specifies a redirection. The redirection maps a file descriptor in the child process.

For example, stderr can be merged into stdout as follows:

pid = spawn(command, :err=>:out)
pid = spawn(command, 2=>1)
pid = spawn(command, STDERR=>:out)
pid = spawn(command, STDERR=>STDOUT)

The hash keys specifies a file descriptor in the child process started by spawn. :err, 2 and STDERR specifies the standard error stream (stderr).

The hash values specifies a file descriptor in the parent process which invokes spawn. :out, 1 and STDOUT specifies the standard output stream (stdout).

In the above example, the standard output in the child process is not specified. So it is inherited from the parent process.

The standard input stream (stdin) can be specified by :in, 0 and STDIN.

A filename can be specified as a hash value.

pid = spawn(command, :in=>"/dev/null") # read mode
pid = spawn(command, :out=>"/dev/null") # write mode
pid = spawn(command, :err=>"log") # write mode
pid = spawn(command, 3=>"/dev/null") # read mode

For stdout and stderr, it is opened in write mode. Otherwise read mode is used.

For specifying flags and permission of file creation explicitly, an array is used instead.

pid = spawn(command, :in=>["file"]) # read mode is assumed
pid = spawn(command, :in=>["file", "r"])
pid = spawn(command, :out=>["log", "w"]) # 0644 assumed
pid = spawn(command, :out=>["log", "w", 0600])
pid = spawn(command, :out=>["log", File::WRONLY|File::EXCL|File::CREAT, 0600])

The array specifies a filename, flags and permission. The flags can be a string or an integer. If the flags is omitted or nil, File::RDONLY is assumed. The permission should be an integer. If the permission is omitted or nil, 0644 is assumed.

If an array of IOs and integers are specified as a hash key, all the elements are redirected.

# stdout and stderr is redirected to log file.
# The file "log" is opened just once.
pid = spawn(command, [:out, :err]=>["log", "w"])

Another way to merge multiple file descriptors is [:child, fd]. [:child, fd] means the file descriptor in the child process. This is different from fd. For example, :err=>:out means redirecting child stderr to parent stdout. But :err=>[:child, :out] means redirecting child stderr to child stdout. They differs if stdout is redirected in the child process as follows.

# stdout and stderr is redirected to log file.
# The file "log" is opened just once.
pid = spawn(command, :out=>["log", "w"], :err=>[:child, :out])

[:child, :out] can be used to merge stderr into stdout in IO.popen. In this case, IO.popen redirects stdout to a pipe in the child process and [:child, :out] refers the redirected stdout.

io = IO.popen(["sh", "-c", "echo out; echo err >&2", :err=>[:child, :out]])
p io.read #=> "out\nerr\n"

spawn closes all non-standard unspecified descriptors by default. The "standard" descriptors are 0, 1 and 2. This behavior is specified by :close_others option. :close_others doesn't affect the standard descriptors which are closed only if :close is specified explicitly.

pid = spawn(command, :close_others=>true)  # close 3,4,5,... (default)
pid = spawn(command, :close_others=>false) # don't close 3,4,5,...

:close_others is true by default for spawn and IO.popen.

So IO.pipe and spawn can be used as IO.popen.

# similar to r = IO.popen(command)
r, w = IO.pipe
pid = spawn(command, :out=>w)   # r, w is closed in the child process.
w.close

:close is specified as a hash value to close a fd individually.

f = open(foo)
system(command, f=>:close)        # don't inherit f.

If a file descriptor need to be inherited, io=>io can be used.

# valgrind has --log-fd option for log destination.
# log_w=>log_w indicates log_w.fileno inherits to child process.
log_r, log_w = IO.pipe
pid = spawn("valgrind", "--log-fd=#{log_w.fileno}", "echo", "a", log_w=>log_w)
log_w.close
p log_r.read

It is also possible to exchange file descriptors.

pid = spawn(command, :out=>:err, :err=>:out)

The hash keys specify file descriptors in the child process. The hash values specifies file descriptors in the parent process. So the above specifies exchanging stdout and stderr. Internally, spawn uses an extra file descriptor to resolve such cyclic file descriptor mapping.

See Kernel.exec for the standard shell.




# File 'process.c'

/*
 *  call-seq:
 *     spawn([env,] command... [,options])     -> pid
 *     Process.spawn([env,] command... [,options])     -> pid
 *
 *  spawn executes specified command and return its pid.
 *
 *  This method doesn't wait for end of the command.
 *  The parent process should
 *  use <code>Process.wait</code> to collect
 *  the termination status of its child or
 *  use <code>Process.detach</code> to register
 *  disinterest in their status;
 *  otherwise, the operating system may accumulate zombie processes.
 *
 *  spawn has bunch of options to specify process attributes:
 *
 *    env: hash
 *      name => val : set the environment variable
 *      name => nil : unset the environment variable
 *    command...:
 *      commandline                 : command line string which is passed to the standard shell
 *      cmdname, arg1, ...          : command name and one or more arguments (no shell)
 *      [cmdname, argv0], arg1, ... : command name, argv[0] and zero or more arguments (no shell)
 *    options: hash
 *      clearing environment variables:
 *        :unsetenv_others => true   : clear environment variables except specified by env
 *        :unsetenv_others => false  : don't clear (default)
 *      process group:
 *        :pgroup => true or 0 : make a new process group
 *        :pgroup => pgid      : join to specified process group
 *        :pgroup => nil       : don't change the process group (default)
 *      resource limit: resourcename is core, cpu, data, etc.  See Process.setrlimit.
 *        :rlimit_resourcename => limit
 *        :rlimit_resourcename => [cur_limit, max_limit]
 *      current directory:
 *        :chdir => str
 *      umask:
 *        :umask => int
 *      redirection:
 *        key:
 *          FD              : single file descriptor in child process
 *          [FD, FD, ...]   : multiple file descriptor in child process
 *        value:
 *          FD                        : redirect to the file descriptor in parent process
 *          string                    : redirect to file with open(string, "r" or "w")
 *          [string]                  : redirect to file with open(string, File::RDONLY)
 *          [string, open_mode]       : redirect to file with open(string, open_mode, 0644)
 *          [string, open_mode, perm] : redirect to file with open(string, open_mode, perm)
 *          [:child, FD]              : redirect to the redirected file descriptor
 *          :close                    : close the file descriptor in child process
 *        FD is one of follows
 *          :in     : the file descriptor 0 which is the standard input
 *          :out    : the file descriptor 1 which is the standard output
 *          :err    : the file descriptor 2 which is the standard error
 *          integer : the file descriptor of specified the integer
 *          io      : the file descriptor specified as io.fileno
 *      file descriptor inheritance: close non-redirected non-standard fds (3, 4, 5, ...) or not
 *        :close_others => false : inherit fds (default for system and exec)
 *        :close_others => true  : don't inherit (default for spawn and IO.popen)
 *
 *  If a hash is given as +env+, the environment is
 *  updated by +env+ before <code>exec(2)</code> in the child process.
 *  If a pair in +env+ has nil as the value, the variable is deleted.
 *
 *    # set FOO as BAR and unset BAZ.
 *    pid = spawn({"FOO"=>"BAR", "BAZ"=>nil}, command)
 *
 *  If a hash is given as +options+,
 *  it specifies
 *  process group,
 *  resource limit,
 *  current directory,
 *  umask and
 *  redirects for the child process.
 *  Also, it can be specified to clear environment variables.
 *
 *  The <code>:unsetenv_others</code> key in +options+ specifies
 *  to clear environment variables, other than specified by +env+.
 *
 *    pid = spawn(command, :unsetenv_others=>true) # no environment variable
 *    pid = spawn({"FOO"=>"BAR"}, command, :unsetenv_others=>true) # FOO only
 *
 *  The <code>:pgroup</code> key in +options+ specifies a process group.
 *  The corresponding value should be true, zero or positive integer.
 *  true and zero means the process should be a process leader of a new
 *  process group.
 *  Other values specifies a process group to be belongs.
 *
 *    pid = spawn(command, :pgroup=>true) # process leader
 *    pid = spawn(command, :pgroup=>10) # belongs to the process group 10
 *
 *  The <code>:rlimit_</code><em>foo</em> key specifies a resource limit.
 *  <em>foo</em> should be one of resource types such as <code>core</code>.
 *  The corresponding value should be an integer or an array which have one or
 *  two integers: same as cur_limit and max_limit arguments for
 *  Process.setrlimit.
 *
 *    cur, max = Process.getrlimit(:CORE)
 *    pid = spawn(command, :rlimit_core=>[0,max]) # disable core temporary.
 *    pid = spawn(command, :rlimit_core=>max) # enable core dump
 *    pid = spawn(command, :rlimit_core=>0) # never dump core.
 *
 *  The <code>:chdir</code> key in +options+ specifies the current directory.
 *
 *    pid = spawn(command, :chdir=>"/var/tmp")
 *
 *  The <code>:umask</code> key in +options+ specifies the umask.
 *
 *    pid = spawn(command, :umask=>077)
 *
 *  The :in, :out, :err, a fixnum, an IO and an array key specifies a redirection.
 *  The redirection maps a file descriptor in the child process.
 *
 *  For example, stderr can be merged into stdout as follows:
 *
 *    pid = spawn(command, :err=>:out)
 *    pid = spawn(command, 2=>1)
 *    pid = spawn(command, STDERR=>:out)
 *    pid = spawn(command, STDERR=>STDOUT)
 *
 *  The hash keys specifies a file descriptor
 *  in the child process started by <code>spawn</code>.
 *  :err, 2 and STDERR specifies the standard error stream (stderr).
 *
 *  The hash values specifies a file descriptor
 *  in the parent process which invokes <code>spawn</code>.
 *  :out, 1 and STDOUT specifies the standard output stream (stdout).
 *
 *  In the above example,
 *  the standard output in the child process is not specified.
 *  So it is inherited from the parent process.
 *
 *  The standard input stream (stdin) can be specified by :in, 0 and STDIN.
 *
 *  A filename can be specified as a hash value.
 *
 *    pid = spawn(command, :in=>"/dev/null") # read mode
 *    pid = spawn(command, :out=>"/dev/null") # write mode
 *    pid = spawn(command, :err=>"log") # write mode
 *    pid = spawn(command, 3=>"/dev/null") # read mode
 *
 *  For stdout and stderr,
 *  it is opened in write mode.
 *  Otherwise read mode is used.
 *
 *  For specifying flags and permission of file creation explicitly,
 *  an array is used instead.
 *
 *    pid = spawn(command, :in=>["file"]) # read mode is assumed
 *    pid = spawn(command, :in=>["file", "r"])
 *    pid = spawn(command, :out=>["log", "w"]) # 0644 assumed
 *    pid = spawn(command, :out=>["log", "w", 0600])
 *    pid = spawn(command, :out=>["log", File::WRONLY|File::EXCL|File::CREAT, 0600])
 *
 *  The array specifies a filename, flags and permission.
 *  The flags can be a string or an integer.
 *  If the flags is omitted or nil, File::RDONLY is assumed.
 *  The permission should be an integer.
 *  If the permission is omitted or nil, 0644 is assumed.
 *
 *  If an array of IOs and integers are specified as a hash key,
 *  all the elements are redirected.
 *
 *    # stdout and stderr is redirected to log file.
 *    # The file "log" is opened just once.
 *    pid = spawn(command, [:out, :err]=>["log", "w"])
 *
 *  Another way to merge multiple file descriptors is [:child, fd].
 *  \[:child, fd] means the file descriptor in the child process.
 *  This is different from fd.
 *  For example, :err=>:out means redirecting child stderr to parent stdout.
 *  But :err=>[:child, :out] means redirecting child stderr to child stdout.
 *  They differs if stdout is redirected in the child process as follows.
 *
 *    # stdout and stderr is redirected to log file.
 *    # The file "log" is opened just once.
 *    pid = spawn(command, :out=>["log", "w"], :err=>[:child, :out])
 *
 *  \[:child, :out] can be used to merge stderr into stdout in IO.popen.
 *  In this case, IO.popen redirects stdout to a pipe in the child process
 *  and [:child, :out] refers the redirected stdout.
 *
 *    io = IO.popen(["sh", "-c", "echo out; echo err >&2", :err=>[:child, :out]])
 *    p io.read #=> "out\nerr\n"
 *
 *  spawn closes all non-standard unspecified descriptors by default.
 *  The "standard" descriptors are 0, 1 and 2.
 *  This behavior is specified by :close_others option.
 *  :close_others doesn't affect the standard descriptors which are
 *  closed only if :close is specified explicitly.
 *
 *    pid = spawn(command, :close_others=>true)  # close 3,4,5,... (default)
 *    pid = spawn(command, :close_others=>false) # don't close 3,4,5,...
 *
 *  :close_others is true by default for spawn and IO.popen.
 *
 *  So IO.pipe and spawn can be used as IO.popen.
 *
 *    # similar to r = IO.popen(command)
 *    r, w = IO.pipe
 *    pid = spawn(command, :out=>w)   # r, w is closed in the child process.
 *    w.close
 *
 *  :close is specified as a hash value to close a fd individually.
 *
 *    f = open(foo)
 *    system(command, f=>:close)        # don't inherit f.
 *
 *  If a file descriptor need to be inherited,
 *  io=>io can be used.
 *
 *    # valgrind has --log-fd option for log destination.
 *    # log_w=>log_w indicates log_w.fileno inherits to child process.
 *    log_r, log_w = IO.pipe
 *    pid = spawn("valgrind", "--log-fd=#{log_w.fileno}", "echo", "a", log_w=>log_w)
 *    log_w.close
 *    p log_r.read
 *
 *  It is also possible to exchange file descriptors.
 *
 *    pid = spawn(command, :out=>:err, :err=>:out)
 *
 *  The hash keys specify file descriptors in the child process.
 *  The hash values specifies file descriptors in the parent process.
 *  So the above specifies exchanging stdout and stderr.
 *  Internally, +spawn+ uses an extra file descriptor to resolve such cyclic
 *  file descriptor mapping.
 *
 *  See <code>Kernel.exec</code> for the standard shell.
 */

static VALUE
rb_f_spawn(int argc, VALUE *argv)
{
    rb_pid_t pid;
    char errmsg[CHILD_ERRMSG_BUFLEN] = { '\0' };
    struct rb_exec_arg earg;

    pid = rb_spawn_process(&earg, rb_exec_arg_prepare(&earg, argc, argv, TRUE), errmsg, sizeof(errmsg));
    if (pid == -1) {
    const char *prog = errmsg;
    if (!prog[0] && !(prog = earg.prog) && earg.argc) {
        prog = RSTRING_PTR(earg.argv[0]);
    }
    rb_sys_fail(prog);
    }
#if defined(HAVE_FORK) || defined(HAVE_SPAWNV)
    return PIDT2NUM(pid);
#else
    return Qnil;
#endif
}

.times ⇒ Object

Returns a Tms structure (see Struct::Tms on page 388) that contains user and system CPU times for this process.

t = Process.times
[ t.utime, t.stime ]   #=> [0.0, 0.02]




# File 'process.c'

/*
 *  call-seq:
 *     Process.times   -> aStructTms
 *
 *  Returns a <code>Tms</code> structure (see <code>Struct::Tms</code>
 *  on page 388) that contains user and system CPU times for this
 *  process.
 *
 *     t = Process.times
 *     [ t.utime, t.stime ]   #=> [0.0, 0.02]
 */

VALUE
rb_proc_times(VALUE obj)
{
    const double hertz =
#ifdef HAVE__SC_CLK_TCK
    (double)sysconf(_SC_CLK_TCK);
#else
#ifndef HZ
# ifdef CLK_TCK
#   define HZ CLK_TCK
# else
#   define HZ 60
# endif
#endif /* HZ */
    HZ;
#endif
    struct tms buf;
    volatile VALUE utime, stime, cutime, sctime;

    times(&buf);
    return rb_struct_new(rb_cProcessTms,
             utime = DBL2NUM(buf.tms_utime / hertz),
             stime = DBL2NUM(buf.tms_stime / hertz),
             cutime = DBL2NUM(buf.tms_cutime / hertz),
             sctime = DBL2NUM(buf.tms_cstime / hertz));
}

.uid ⇒ Fixnum .Process::UID.rid ⇒ Fixnum .Process::Sys.getuid ⇒ Fixnum

Returns the (real) user ID of this process.

Process.uid   #=> 501

Overloads:




# File 'process.c'

/*
 *  call-seq:
 *     Process.uid           -> fixnum
 *     Process::UID.rid      -> fixnum
 *     Process::Sys.getuid   -> fixnum
 *
 *  Returns the (real) user ID of this process.
 *
 *     Process.uid   #=> 501
 */

static VALUE
proc_getuid(VALUE obj)
{
    rb_uid_t uid = getuid();
    return UIDT2NUM(uid);
}

.uid=(integer) ⇒ Numeric

Sets the (integer) user ID for this process. Not available on all platforms.

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.uid= integer   -> numeric
 *
 *  Sets the (integer) user ID for this process. Not available on all
 *  platforms.
 */

static VALUE
proc_setuid(VALUE obj, VALUE id)
{
    rb_uid_t uid;

    check_uid_switch();

    uid = NUM2UIDT(id);
#if defined(HAVE_SETRESUID)
    if (setresuid(uid, -1, -1) < 0) rb_sys_fail(0);
#elif defined HAVE_SETREUID
    if (setreuid(uid, -1) < 0) rb_sys_fail(0);
#elif defined HAVE_SETRUID
    if (setruid(uid) < 0) rb_sys_fail(0);
#elif defined HAVE_SETUID
    {
    if (geteuid() == uid) {
        if (setuid(uid) < 0) rb_sys_fail(0);
    }
    else {
        rb_notimplement();
    }
    }
#endif
    return id;
}

.wait ⇒ Fixnum .wait(pid = -1, flags = 0) ⇒ Fixnum .waitpid(pid = -1, flags = 0) ⇒ Fixnum

Waits for a child process to exit, returns its process id, and sets $? to a Process::Status object containing information on that process. Which child it waits on depends on the value of pid:

> 0

Waits for the child whose process ID equals pid.

0

Waits for any child whose process group ID equals that of the calling process.

-1

Waits for any child process (the default if no pid is given).

< -1

Waits for any child whose process group ID equals the absolute value of pid.

The flags argument may be a logical or of the flag values Process::WNOHANG (do not block if no child available) or Process::WUNTRACED (return stopped children that haven't been reported). Not all flags are available on all platforms, but a flag value of zero will work on all platforms.

Calling this method raises a SystemError if there are no child processes. Not available on all platforms.

include Process
fork { exit 99 }                 #=> 27429
wait                             #=> 27429
$?.exitstatus                    #=> 99

pid = fork { sleep 3 }           #=> 27440
Time.now                         #=> 2008-03-08 19:56:16 +0900
waitpid(pid, Process::WNOHANG)   #=> nil
Time.now                         #=> 2008-03-08 19:56:16 +0900
waitpid(pid, 0)                  #=> 27440
Time.now                         #=> 2008-03-08 19:56:19 +0900

Overloads:




# File 'process.c'

/*
 *  call-seq:
 *     Process.wait()                     -> fixnum
 *     Process.wait(pid=-1, flags=0)      -> fixnum
 *     Process.waitpid(pid=-1, flags=0)   -> fixnum
 *
 *  Waits for a child process to exit, returns its process id, and
 *  sets <code>$?</code> to a <code>Process::Status</code> object
 *  containing information on that process. Which child it waits on
 *  depends on the value of _pid_:
 *
 *  > 0::   Waits for the child whose process ID equals _pid_.
 *
 *  0::     Waits for any child whose process group ID equals that of the
 *          calling process.
 *
 *  -1::    Waits for any child process (the default if no _pid_ is
 *          given).
 *
 *  < -1::  Waits for any child whose process group ID equals the absolute
 *          value of _pid_.
 *
 *  The _flags_ argument may be a logical or of the flag values
 *  <code>Process::WNOHANG</code> (do not block if no child available)
 *  or <code>Process::WUNTRACED</code> (return stopped children that
 *  haven't been reported). Not all flags are available on all
 *  platforms, but a flag value of zero will work on all platforms.
 *
 *  Calling this method raises a <code>SystemError</code> if there are
 *  no child processes. Not available on all platforms.
 *
 *     include Process
 *     fork { exit 99 }                 #=> 27429
 *     wait                             #=> 27429
 *     $?.exitstatus                    #=> 99
 *
 *     pid = fork { sleep 3 }           #=> 27440
 *     Time.now                         #=> 2008-03-08 19:56:16 +0900
 *     waitpid(pid, Process::WNOHANG)   #=> nil
 *     Time.now                         #=> 2008-03-08 19:56:16 +0900
 *     waitpid(pid, 0)                  #=> 27440
 *     Time.now                         #=> 2008-03-08 19:56:19 +0900
 */

static VALUE
proc_wait(int argc, VALUE *argv)
{
    VALUE vpid, vflags;
    rb_pid_t pid;
    int flags, status;

    rb_secure(2);
    flags = 0;
    if (argc == 0) {
    pid = -1;
    }
    else {
    rb_scan_args(argc, argv, "02", &vpid, &vflags);
    pid = NUM2PIDT(vpid);
    if (argc == 2 && !NIL_P(vflags)) {
        flags = NUM2UINT(vflags);
    }
    }
    if ((pid = rb_waitpid(pid, &status, flags)) < 0)
    rb_sys_fail(0);
    if (pid == 0) {
    rb_last_status_clear();
    return Qnil;
    }
    return PIDT2NUM(pid);
}

.wait2(pid = -1, flags = 0) ⇒ Array .waitpid2(pid = -1, flags = 0) ⇒ Array

Waits for a child process to exit (see Process::waitpid for exact semantics) and returns an array containing the process id and the exit status (a Process::Status object) of that child. Raises a SystemError if there are no child processes.

Process.fork { exit 99 }   #=> 27437
pid, status = Process.wait2
pid                        #=> 27437
status.exitstatus          #=> 99

Overloads:

  • .wait2(pid = -1, flags = 0) ⇒ Array

    Returns:

  • .waitpid2(pid = -1, flags = 0) ⇒ Array

    Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.wait2(pid=-1, flags=0)      -> [pid, status]
 *     Process.waitpid2(pid=-1, flags=0)   -> [pid, status]
 *
 *  Waits for a child process to exit (see Process::waitpid for exact
 *  semantics) and returns an array containing the process id and the
 *  exit status (a <code>Process::Status</code> object) of that
 *  child. Raises a <code>SystemError</code> if there are no child
 *  processes.
 *
 *     Process.fork { exit 99 }   #=> 27437
 *     pid, status = Process.wait2
 *     pid                        #=> 27437
 *     status.exitstatus          #=> 99
 */

static VALUE
proc_wait2(int argc, VALUE *argv)
{
    VALUE pid = proc_wait(argc, argv);
    if (NIL_P(pid)) return Qnil;
    return rb_assoc_new(pid, rb_last_status_get());
}

.waitall ⇒ Array

Waits for all children, returning an array of pid/status pairs (where status is a Process::Status object).

fork { sleep 0.2; exit 2 }   #=> 27432
fork { sleep 0.1; exit 1 }   #=> 27433
fork {            exit 0 }   #=> 27434
p Process.waitall

produces:

[[27434, #<Process::Status: pid=27434,exited(0)>],
 [27433, #<Process::Status: pid=27433,exited(1)>],
 [27432, #<Process::Status: pid=27432,exited(2)>]]

Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.waitall   -> [ [pid1,status1], ...]
 *
 *  Waits for all children, returning an array of
 *  _pid_/_status_ pairs (where _status_ is a
 *  <code>Process::Status</code> object).
 *
 *     fork { sleep 0.2; exit 2 }   #=> 27432
 *     fork { sleep 0.1; exit 1 }   #=> 27433
 *     fork {            exit 0 }   #=> 27434
 *     p Process.waitall
 *
 *  <em>produces</em>:
 *
 *     [[27434, #<Process::Status: pid=27434,exited(0)>],
 *      [27433, #<Process::Status: pid=27433,exited(1)>],
 *      [27432, #<Process::Status: pid=27432,exited(2)>]]
 */

static VALUE
proc_waitall(void)
{
    VALUE result;
    rb_pid_t pid;
    int status;

    rb_secure(2);
    result = rb_ary_new();
#ifdef NO_WAITPID
    if (pid_tbl) {
    st_foreach(pid_tbl, waitall_each, result);
    }
#else
    rb_last_status_clear();
#endif

    for (pid = -1;;) {
#ifdef NO_WAITPID
    pid = wait(&status);
#else
    pid = rb_waitpid(-1, &status, 0);
#endif
    if (pid == -1) {
        if (errno == ECHILD)
        break;
#ifdef NO_WAITPID
        if (errno == EINTR) {
        rb_thread_schedule();
        continue;
        }
#endif
        rb_sys_fail(0);
    }
#ifdef NO_WAITPID
    rb_last_status_set(status, pid);
#endif
    rb_ary_push(result, rb_assoc_new(PIDT2NUM(pid), rb_last_status_get()));
    }
    return result;
}

.wait ⇒ Fixnum .wait(pid = -1, flags = 0) ⇒ Fixnum .waitpid(pid = -1, flags = 0) ⇒ Fixnum

Waits for a child process to exit, returns its process id, and sets $? to a Process::Status object containing information on that process. Which child it waits on depends on the value of pid:

> 0

Waits for the child whose process ID equals pid.

0

Waits for any child whose process group ID equals that of the calling process.

-1

Waits for any child process (the default if no pid is given).

< -1

Waits for any child whose process group ID equals the absolute value of pid.

The flags argument may be a logical or of the flag values Process::WNOHANG (do not block if no child available) or Process::WUNTRACED (return stopped children that haven't been reported). Not all flags are available on all platforms, but a flag value of zero will work on all platforms.

Calling this method raises a SystemError if there are no child processes. Not available on all platforms.

include Process
fork { exit 99 }                 #=> 27429
wait                             #=> 27429
$?.exitstatus                    #=> 99

pid = fork { sleep 3 }           #=> 27440
Time.now                         #=> 2008-03-08 19:56:16 +0900
waitpid(pid, Process::WNOHANG)   #=> nil
Time.now                         #=> 2008-03-08 19:56:16 +0900
waitpid(pid, 0)                  #=> 27440
Time.now                         #=> 2008-03-08 19:56:19 +0900

Overloads:




# File 'process.c'

/*
 *  call-seq:
 *     Process.wait()                     -> fixnum
 *     Process.wait(pid=-1, flags=0)      -> fixnum
 *     Process.waitpid(pid=-1, flags=0)   -> fixnum
 *
 *  Waits for a child process to exit, returns its process id, and
 *  sets <code>$?</code> to a <code>Process::Status</code> object
 *  containing information on that process. Which child it waits on
 *  depends on the value of _pid_:
 *
 *  > 0::   Waits for the child whose process ID equals _pid_.
 *
 *  0::     Waits for any child whose process group ID equals that of the
 *          calling process.
 *
 *  -1::    Waits for any child process (the default if no _pid_ is
 *          given).
 *
 *  < -1::  Waits for any child whose process group ID equals the absolute
 *          value of _pid_.
 *
 *  The _flags_ argument may be a logical or of the flag values
 *  <code>Process::WNOHANG</code> (do not block if no child available)
 *  or <code>Process::WUNTRACED</code> (return stopped children that
 *  haven't been reported). Not all flags are available on all
 *  platforms, but a flag value of zero will work on all platforms.
 *
 *  Calling this method raises a <code>SystemError</code> if there are
 *  no child processes. Not available on all platforms.
 *
 *     include Process
 *     fork { exit 99 }                 #=> 27429
 *     wait                             #=> 27429
 *     $?.exitstatus                    #=> 99
 *
 *     pid = fork { sleep 3 }           #=> 27440
 *     Time.now                         #=> 2008-03-08 19:56:16 +0900
 *     waitpid(pid, Process::WNOHANG)   #=> nil
 *     Time.now                         #=> 2008-03-08 19:56:16 +0900
 *     waitpid(pid, 0)                  #=> 27440
 *     Time.now                         #=> 2008-03-08 19:56:19 +0900
 */

static VALUE
proc_wait(int argc, VALUE *argv)
{
    VALUE vpid, vflags;
    rb_pid_t pid;
    int flags, status;

    rb_secure(2);
    flags = 0;
    if (argc == 0) {
    pid = -1;
    }
    else {
    rb_scan_args(argc, argv, "02", &vpid, &vflags);
    pid = NUM2PIDT(vpid);
    if (argc == 2 && !NIL_P(vflags)) {
        flags = NUM2UINT(vflags);
    }
    }
    if ((pid = rb_waitpid(pid, &status, flags)) < 0)
    rb_sys_fail(0);
    if (pid == 0) {
    rb_last_status_clear();
    return Qnil;
    }
    return PIDT2NUM(pid);
}

.wait2(pid = -1, flags = 0) ⇒ Array .waitpid2(pid = -1, flags = 0) ⇒ Array

Waits for a child process to exit (see Process::waitpid for exact semantics) and returns an array containing the process id and the exit status (a Process::Status object) of that child. Raises a SystemError if there are no child processes.

Process.fork { exit 99 }   #=> 27437
pid, status = Process.wait2
pid                        #=> 27437
status.exitstatus          #=> 99

Overloads:

  • .wait2(pid = -1, flags = 0) ⇒ Array

    Returns:

  • .waitpid2(pid = -1, flags = 0) ⇒ Array

    Returns:




# File 'process.c'

/*
 *  call-seq:
 *     Process.wait2(pid=-1, flags=0)      -> [pid, status]
 *     Process.waitpid2(pid=-1, flags=0)   -> [pid, status]
 *
 *  Waits for a child process to exit (see Process::waitpid for exact
 *  semantics) and returns an array containing the process id and the
 *  exit status (a <code>Process::Status</code> object) of that
 *  child. Raises a <code>SystemError</code> if there are no child
 *  processes.
 *
 *     Process.fork { exit 99 }   #=> 27437
 *     pid, status = Process.wait2
 *     pid                        #=> 27437
 *     status.exitstatus          #=> 99
 */

static VALUE
proc_wait2(int argc, VALUE *argv)
{
    VALUE pid = proc_wait(argc, argv);
    if (NIL_P(pid)) return Qnil;
    return rb_assoc_new(pid, rb_last_status_get());
}