The Process module is a collection of methods used to manipulate processes.
see Process.wait
Maximum size of the process’s virtual memory (address space) in bytes.
see the system getrlimit(2) manual for details.
Maximum size of the core file.
see the system getrlimit(2) manual for details.
CPU time limit in seconds.
see the system getrlimit(2) manual for details.
Maximum size of the process’s data segment.
see the system getrlimit(2) manual for details.
Maximum size of files that the process may create.
see the system getrlimit(2) manual for details.
Maximum number of bytes of memory that may be locked into RAM.
see the system getrlimit(2) manual for details.
Specifies the limit on the number of bytes that can be allocated for POSIX message queues for the real user ID of the calling process.
see the system getrlimit(2) manual for details.
Specifies a ceiling to which the process’s nice value can be raised.
see the system getrlimit(2) manual for details.
Specifies a value one greater than the maximum file descriptor number that can be opened by this process.
see the system getrlimit(2) manual for details.
The maximum number of processes that can be created for the real user ID of the calling process.
see the system getrlimit(2) manual for details.
Specifies the limit (in pages) of the process’s resident set.
see the system getrlimit(2) manual for details.
Specifies a ceiling on the real-time priority that may be set for this process.
see the system getrlimit(2) manual for details.
Specifies limit on CPU time this process scheduled under a real-time scheduling policy can consume.
see the system getrlimit(2) manual for details.
Maximum size of the socket buffer.
Specifies a limit on the number of signals that may be queued for the real user ID of the calling process.
see the system getrlimit(2) manual for details.
Maximum size of the stack, in bytes.
see the system getrlimit(2) manual for details.
VALUE
rb_f_abort(int argc, const VALUE *argv)
{
rb_check_arity(argc, 0, 1);
if (argc == 0) {
if (!NIL_P(GET_THREAD()->errinfo)) {
ruby_error_print();
}
rb_exit(EXIT_FAILURE);
}
else {
VALUE args[2];
args[1] = args[0] = argv[0];
StringValue(args[0]);
rb_io_puts(1, args, rb_stderr);
args[0] = INT2NUM(EXIT_FAILURE);
rb_exc_raise(rb_class_new_instance(2, args, rb_eSystemExit));
}
UNREACHABLE;
}
Terminate execution immediately, effectively by calling Kernel.exit(false). If msg is given, it is written to STDERR prior to terminating.
static VALUE
proc_argv0(VALUE process)
{
return rb_orig_progname;
}
Returns the name of the script being executed. The value is not affected by assigning a new value to $0.
This method first appeared in Ruby 2.1 to serve as a global variable free means to get the script name.
VALUE
rb_clock_getres(int argc, VALUE *argv)
{
VALUE clk_id, unit;
struct timetick tt;
timetick_int_t numerators[2];
timetick_int_t denominators[2];
int num_numerators = 0;
int num_denominators = 0;
rb_scan_args(argc, argv, "11", &clk_id, &unit);
if (SYMBOL_P(clk_id)) {
#ifdef RUBY_GETTIMEOFDAY_BASED_CLOCK_REALTIME
if (clk_id == RUBY_GETTIMEOFDAY_BASED_CLOCK_REALTIME) {
tt.giga_count = 0;
tt.count = 1000;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
#ifdef RUBY_TIME_BASED_CLOCK_REALTIME
if (clk_id == RUBY_TIME_BASED_CLOCK_REALTIME) {
tt.giga_count = 1;
tt.count = 0;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
#ifdef RUBY_TIMES_BASED_CLOCK_MONOTONIC
if (clk_id == RUBY_TIMES_BASED_CLOCK_MONOTONIC) {
tt.count = 1;
tt.giga_count = 0;
denominators[num_denominators++] = get_clk_tck();
goto success;
}
#endif
#ifdef RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
if (clk_id == RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID) {
tt.giga_count = 0;
tt.count = 1000;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
#ifdef RUBY_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID
if (clk_id == RUBY_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID) {
tt.count = 1;
tt.giga_count = 0;
denominators[num_denominators++] = get_clk_tck();
goto success;
}
#endif
#ifdef RUBY_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID
if (clk_id == RUBY_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID) {
tt.count = 1;
tt.giga_count = 0;
denominators[num_denominators++] = CLOCKS_PER_SEC;
goto success;
}
#endif
#ifdef RUBY_MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC
if (clk_id == RUBY_MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC) {
mach_timebase_info_data_t *info = get_mach_timebase_info();
tt.count = 1;
tt.giga_count = 0;
numerators[num_numerators++] = info->numer;
denominators[num_denominators++] = info->denom;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
}
else {
#if defined(HAVE_CLOCK_GETRES)
struct timespec ts;
clockid_t c = NUM2CLOCKID(clk_id);
int ret = clock_getres(c, &ts);
if (ret == -1)
rb_sys_fail("clock_getres");
tt.count = (int32_t)ts.tv_nsec;
tt.giga_count = ts.tv_sec;
denominators[num_denominators++] = 1000000000;
goto success;
#endif
}
/* EINVAL emulates clock_getres behavior when clock_id is invalid. */
rb_syserr_fail(EINVAL, 0);
success:
if (unit == ID2SYM(id_hertz)) {
return timetick2dblnum_reciprocal(&tt, numerators, num_numerators, denominators, num_denominators);
}
else {
return make_clock_result(&tt, numerators, num_numerators, denominators, num_denominators, unit);
}
}
Returns the time resolution returned by POSIX clock_getres() function.
clock_id specifies a kind of clock. See the document of Process.clock_gettime for details.
clock_id can be a symbol as Process.clock_gettime. However the result may not be accurate. For example, +Process.clock_getres(:GETTIMEOFDAY_BASED_CLOCK_REALTIME)+ returns 1.0e-06 which means 1 microsecond, but actual resolution can be more coarse.
If the given clock_id is not supported, Errno::EINVAL is raised.
unit specifies a type of the return value. Process.clock_getres accepts unit as Process.clock_gettime. The default value, :float_second, is also same as Process.clock_gettime.
Process.clock_getres also accepts :hertz as unit. :hertz means a the reciprocal of :float_second.
:hertz can be used to obtain the exact value of the clock ticks per second for times() function and CLOCKS_PER_SEC for clock() function.
+Process.clock_getres(:TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz)+ returns the clock ticks per second.
+Process.clock_getres(:CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz)+ returns CLOCKS_PER_SEC.
p Process.clock_getres(Process::CLOCK_MONOTONIC) #=> 1.0e-09
VALUE
rb_clock_gettime(int argc, VALUE *argv)
{
VALUE clk_id, unit;
int ret;
struct timetick tt;
timetick_int_t numerators[2];
timetick_int_t denominators[2];
int num_numerators = 0;
int num_denominators = 0;
rb_scan_args(argc, argv, "11", &clk_id, &unit);
if (SYMBOL_P(clk_id)) {
/*
* Non-clock_gettime clocks are provided by symbol clk_id.
*
* gettimeofday is always available on platforms supported by Ruby.
* GETTIMEOFDAY_BASED_CLOCK_REALTIME is used for
* CLOCK_REALTIME if clock_gettime is not available.
*/
#define RUBY_GETTIMEOFDAY_BASED_CLOCK_REALTIME ID2SYM(id_GETTIMEOFDAY_BASED_CLOCK_REALTIME)
if (clk_id == RUBY_GETTIMEOFDAY_BASED_CLOCK_REALTIME) {
struct timeval tv;
ret = gettimeofday(&tv, 0);
if (ret != 0)
rb_sys_fail("gettimeofday");
tt.giga_count = tv.tv_sec;
tt.count = (int32_t)tv.tv_usec * 1000;
denominators[num_denominators++] = 1000000000;
goto success;
}
#define RUBY_TIME_BASED_CLOCK_REALTIME ID2SYM(id_TIME_BASED_CLOCK_REALTIME)
if (clk_id == RUBY_TIME_BASED_CLOCK_REALTIME) {
time_t t;
t = time(NULL);
if (t == (time_t)-1)
rb_sys_fail("time");
tt.giga_count = t;
tt.count = 0;
denominators[num_denominators++] = 1000000000;
goto success;
}
#ifdef HAVE_TIMES
#define RUBY_TIMES_BASED_CLOCK_MONOTONIC \
ID2SYM(id_TIMES_BASED_CLOCK_MONOTONIC)
if (clk_id == RUBY_TIMES_BASED_CLOCK_MONOTONIC) {
struct tms buf;
clock_t c;
unsigned_clock_t uc;
c = times(&buf);
if (c == (clock_t)-1)
rb_sys_fail("times");
uc = (unsigned_clock_t)c;
tt.count = (int32_t)(uc % 1000000000);
tt.giga_count = (uc / 1000000000);
denominators[num_denominators++] = get_clk_tck();
goto success;
}
#endif
#ifdef RUSAGE_SELF
#define RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID \
ID2SYM(id_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID)
if (clk_id == RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID) {
struct rusage usage;
int32_t usec;
ret = getrusage(RUSAGE_SELF, &usage);
if (ret != 0)
rb_sys_fail("getrusage");
tt.giga_count = usage.ru_utime.tv_sec + usage.ru_stime.tv_sec;
usec = (int32_t)(usage.ru_utime.tv_usec + usage.ru_stime.tv_usec);
if (1000000 <= usec) {
tt.giga_count++;
usec -= 1000000;
}
tt.count = usec * 1000;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
#ifdef HAVE_TIMES
#define RUBY_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID \
ID2SYM(id_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID)
if (clk_id == RUBY_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID) {
struct tms buf;
unsigned_clock_t utime, stime;
if (times(&buf) == (clock_t)-1)
rb_sys_fail("times");
utime = (unsigned_clock_t)buf.tms_utime;
stime = (unsigned_clock_t)buf.tms_stime;
tt.count = (int32_t)((utime % 1000000000) + (stime % 1000000000));
tt.giga_count = (utime / 1000000000) + (stime / 1000000000);
if (1000000000 <= tt.count) {
tt.count -= 1000000000;
tt.giga_count++;
}
denominators[num_denominators++] = get_clk_tck();
goto success;
}
#endif
#define RUBY_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID \
ID2SYM(id_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID)
if (clk_id == RUBY_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID) {
clock_t c;
unsigned_clock_t uc;
errno = 0;
c = clock();
if (c == (clock_t)-1)
rb_sys_fail("clock");
uc = (unsigned_clock_t)c;
tt.count = (int32_t)(uc % 1000000000);
tt.giga_count = uc / 1000000000;
denominators[num_denominators++] = CLOCKS_PER_SEC;
goto success;
}
#ifdef __APPLE__
#define RUBY_MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC ID2SYM(id_MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC)
if (clk_id == RUBY_MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC) {
mach_timebase_info_data_t *info = get_mach_timebase_info();
uint64_t t = mach_absolute_time();
tt.count = (int32_t)(t % 1000000000);
tt.giga_count = t / 1000000000;
numerators[num_numerators++] = info->numer;
denominators[num_denominators++] = info->denom;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
}
else {
#if defined(HAVE_CLOCK_GETTIME)
struct timespec ts;
clockid_t c;
c = NUM2CLOCKID(clk_id);
ret = clock_gettime(c, &ts);
if (ret == -1)
rb_sys_fail("clock_gettime");
tt.count = (int32_t)ts.tv_nsec;
tt.giga_count = ts.tv_sec;
denominators[num_denominators++] = 1000000000;
goto success;
#endif
}
/* EINVAL emulates clock_gettime behavior when clock_id is invalid. */
rb_syserr_fail(EINVAL, 0);
success:
return make_clock_result(&tt, numerators, num_numerators, denominators, num_denominators, unit);
}
Returns a time returned by POSIX clock_gettime() function.
p Process.clock_gettime(Process::CLOCK_MONOTONIC) #=> 896053.968060096
clock_id specifies a kind of clock. It is specified as a constant which begins with Process::CLOCK_ such as Process::CLOCK_REALTIME and Process::CLOCK_MONOTONIC.
The supported constants depends on OS and version. Ruby provides following types of clock_id if available.
CLOCK_REALTIME-
SUSv2 to 4, Linux 2.5.63, FreeBSD 3.0, NetBSD 2.0, OpenBSD 2.1
CLOCK_MONOTONIC-
SUSv3 to 4, Linux 2.5.63, FreeBSD 3.0, NetBSD 2.0, OpenBSD 3.4
CLOCK_PROCESS_CPUTIME_ID-
SUSv3 to 4, Linux 2.5.63, OpenBSD 5.4
CLOCK_THREAD_CPUTIME_ID-
SUSv3 to 4, Linux 2.5.63, FreeBSD 7.1, OpenBSD 5.4
CLOCK_VIRTUAL-
FreeBSD 3.0, OpenBSD 2.1
CLOCK_PROF-
FreeBSD 3.0, OpenBSD 2.1
CLOCK_REALTIME_FAST-
FreeBSD 8.1
CLOCK_REALTIME_PRECISE-
FreeBSD 8.1
CLOCK_REALTIME_COARSE-
Linux 2.6.32
CLOCK_REALTIME_ALARM-
Linux 3.0
CLOCK_MONOTONIC_FAST-
FreeBSD 8.1
CLOCK_MONOTONIC_PRECISE-
FreeBSD 8.1
CLOCK_MONOTONIC_COARSE-
Linux 2.6.32
CLOCK_MONOTONIC_RAW-
Linux 2.6.28
CLOCK_BOOTTIME-
Linux 2.6.39
CLOCK_BOOTTIME_ALARM-
Linux 3.0
CLOCK_UPTIME-
FreeBSD 7.0, OpenBSD 5.5
CLOCK_UPTIME_FAST-
FreeBSD 8.1
CLOCK_UPTIME_PRECISE-
FreeBSD 8.1
CLOCK_SECOND-
FreeBSD 8.1
Note that SUS stands for Single Unix Specification. SUS contains POSIX and clock_gettime is defined in the POSIX part. SUS defines CLOCK_REALTIME mandatory but CLOCK_MONOTONIC, CLOCK_PROCESS_CPUTIME_ID and CLOCK_THREAD_CPUTIME_ID are optional.
Also, several symbols are accepted as clock_id. There are emulations for clock_gettime().
For example, Process::CLOCK_REALTIME is defined as :GETTIMEOFDAY_BASED_CLOCK_REALTIME when clock_gettime() is not available.
Emulations for CLOCK_REALTIME:
- :GETTIMEOFDAY_BASED_CLOCK_REALTIME
-
Use gettimeofday() defined by SUS. (SUSv4 obsoleted it, though.) The resolution is 1 microsecond.
- :TIME_BASED_CLOCK_REALTIME
-
Use time() defined by ISO C. The resolution is 1 second.
Emulations for CLOCK_MONOTONIC:
- :MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC
-
Use mach_absolute_time(), available on Darwin. The resolution is CPU dependent.
- :TIMES_BASED_CLOCK_MONOTONIC
-
Use the result value of times() defined by POSIX. POSIX defines it as “times() shall return the elapsed real time, in clock ticks, since an arbitrary point in the past (for example, system start-up time)”. For example, GNU/Linux returns a value based on jiffies and it is monotonic. However, 4.4BSD uses gettimeofday() and it is not monotonic. (FreeBSD uses
clock_gettime(CLOCK_MONOTONIC) instead, though.) The resolution is the clock tick. “getconf CLK_TCK” command shows the clock ticks per second. (The clock ticks per second is defined by HZ macro in older systems.) If it is 100 and clock_t is 32 bits integer type, the resolution is 10 millisecond and cannot represent over 497 days.
Emulations for CLOCK_PROCESS_CPUTIME_ID:
- :GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
-
Use getrusage() defined by SUS. getrusage() is used with RUSAGE_SELF to obtain the time only for the calling process (excluding the time for child processes). The result is addition of user time (ru_utime) and system time (ru_stime). The resolution is 1 microsecond.
- :TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID
-
Use times() defined by POSIX. The result is addition of user time (tms_utime) and system time (tms_stime). tms_cutime and tms_cstime are ignored to exclude the time for child processes. The resolution is the clock tick. “getconf CLK_TCK” command shows the clock ticks per second. (The clock ticks per second is defined by HZ macro in older systems.) If it is 100, the resolution is 10 millisecond.
- :CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID
-
Use clock() defined by ISO C. The resolution is 1/CLOCKS_PER_SEC. CLOCKS_PER_SEC is the C-level macro defined by time.h. SUS defines CLOCKS_PER_SEC is 1000000. Non-Unix systems may define it a different value, though. If CLOCKS_PER_SEC is 1000000 as SUS, the resolution is 1 microsecond. If CLOCKS_PER_SEC is 1000000 and clock_t is 32 bits integer type, it cannot represent over 72 minutes.
If the given clock_id is not supported, Errno::EINVAL is raised.
unit specifies a type of the return value.
- :float_second
-
number of seconds as a float (default)
- :float_millisecond
-
number of milliseconds as a float
- :float_microsecond
-
number of microseconds as a float
- :second
-
number of seconds as an integer
- :millisecond
-
number of milliseconds as an integer
- :microsecond
-
number of microseconds as an integer
- :nanosecond
-
number of nanoseconds as an integer
The underlying function, clock_gettime(), returns a number of nanoseconds. Float object (IEEE 754 double) is not enough to represent the return value for CLOCK_REALTIME. If the exact nanoseconds value is required, use :nanoseconds as the unit.
The origin (zero) of the returned value varies. For example, system start up time, process start up time, the Epoch, etc.
The origin in CLOCK_REALTIME is defined as the Epoch (1970-01-01 00:00:00 UTC). But some systems count leap seconds and others doesn’t. So the result can be interpreted differently across systems. Time.now is recommended over CLOCK_REALTIME.
static VALUE
proc_daemon(int argc, VALUE *argv)
{
VALUE nochdir, noclose;
int n;
rb_scan_args(argc, argv, "02", &nochdir, &noclose);
prefork();
n = rb_daemon(RTEST(nochdir), RTEST(noclose));
if (n < 0) rb_sys_fail("daemon");
return INT2FIX(n);
}
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_detach(VALUE obj, VALUE pid)
{
return rb_detach_process(NUM2PIDT(pid));
}
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 intend 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)
static VALUE
proc_getegid(VALUE obj)
{
rb_gid_t egid = getegid();
return GIDT2NUM(egid);
}
Returns the effective group ID for this process. Not available on all platforms.
Process.egid #=> 500
static VALUE
proc_setegid(VALUE obj, VALUE egid)
{
#if defined(HAVE_SETRESGID) || defined(HAVE_SETREGID) || defined(HAVE_SETEGID) || defined(HAVE_SETGID)
rb_gid_t gid;
#endif
check_gid_switch();
#if defined(HAVE_SETRESGID) || defined(HAVE_SETREGID) || defined(HAVE_SETEGID) || defined(HAVE_SETGID)
gid = OBJ2GID(egid);
#endif
#if defined(HAVE_SETRESGID)
if (setresgid(-1, gid, -1) < 0) rb_sys_fail(0);
#elif defined HAVE_SETREGID
if (setregid(-1, gid) < 0) rb_sys_fail(0);
#elif defined HAVE_SETEGID
if (setegid(gid) < 0) rb_sys_fail(0);
#elif defined HAVE_SETGID
if (gid == getgid()) {
if (setgid(gid) < 0) rb_sys_fail(0);
}
else {
rb_notimplement();
}
#else
rb_notimplement();
#endif
return egid;
}
Sets the effective group ID for this process. Not available on all platforms.
static VALUE
proc_geteuid(VALUE obj)
{
rb_uid_t euid = geteuid();
return UIDT2NUM(euid);
}
Returns the effective user ID for this process.
Process.euid #=> 501
static VALUE
proc_seteuid_m(VALUE mod, VALUE euid)
{
check_uid_switch();
proc_seteuid(OBJ2UID(euid));
return euid;
}
Sets the effective user ID for this process. Not available on all platforms.
VALUE
rb_f_exec(int argc, const VALUE *argv)
{
VALUE execarg_obj, fail_str;
struct rb_execarg *eargp;
#define CHILD_ERRMSG_BUFLEN 80
char errmsg[CHILD_ERRMSG_BUFLEN] = { '\0' };
int err;
execarg_obj = rb_execarg_new(argc, argv, TRUE);
eargp = rb_execarg_get(execarg_obj);
before_exec(); /* stop timer thread before redirects */
rb_execarg_parent_start(execarg_obj);
fail_str = eargp->use_shell ? eargp->invoke.sh.shell_script : eargp->invoke.cmd.command_name;
rb_exec_async_signal_safe(eargp, errmsg, sizeof(errmsg));
err = errno;
after_exec(); /* restart timer thread */
rb_exec_fail(eargp, err, errmsg);
RB_GC_GUARD(execarg_obj);
rb_syserr_fail_str(err, fail_str);
return Qnil; /* dummy */
}
Replaces the current process by running the given external command, which can take one of the following forms:
exec(commandline)-
command line string which is passed to the standard shell
exec(cmdname, arg1, ...)-
command name and one or more arguments (no shell)
exec([cmdname, argv0], arg1, ...)-
command name, argv and zero or more arguments (no shell)
In the first form, the string is taken as a command line that is subject to shell expansion before being executed.
The standard shell always means "/bin/sh" on Unix-like systems, same as ENV["RUBYSHELL"] (or ENV["COMSPEC"] on Windows NT series), and similar.
If the string from the first form (exec("command")) follows these simple rules:
-
no meta characters
-
no shell reserved word and no special built-in
-
Ruby invokes the command directly without shell
You can force shell invocation by adding “;” to the string (because “;” is a meta character).
Note that this behavior is observable by pid obtained (return value of spawn() and IO#pid for IO.popen) is the pid of the invoked command, not shell.
In the second form (exec("command1", "arg1", ...)), the first is taken as a command name and the rest are passed as parameters to command with no shell expansion.
In the third form (exec(["command", "argv0"], "arg1", ...)), starting 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 are used, so the running command may inherit some of the environment of the original program (including open file descriptors).
This behavior is modified by the given env and options parameters. See ::spawn for details.
If the command fails to execute (typically Errno::ENOENT when it was not found) a SystemCallError exception is raised.
This method modifies process attributes according to given options before exec(2) system call. See ::spawn for more details about the given options.
The modified attributes may be retained when exec(2) system call fails.
For example, hard resource limits are not restorable.
Consider to create a child process using ::spawn or Kernel#system if this is not acceptable.
exec "echo *" # echoes list of files in current directory # never get here exec "echo", "*" # echoes an asterisk # never get here
VALUE
rb_f_exit(int argc, const VALUE *argv)
{
VALUE status;
int istatus;
if (argc > 0 && rb_scan_args(argc, argv, "01", &status) == 1) {
istatus = exit_status_code(status);
}
else {
istatus = EXIT_SUCCESS;
}
rb_exit(istatus);
UNREACHABLE;
}
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
static VALUE
rb_f_exit_bang(int argc, VALUE *argv, VALUE obj)
{
VALUE status;
int istatus;
if (argc > 0 && rb_scan_args(argc, argv, "01", &status) == 1) {
istatus = exit_status_code(status);
}
else {
istatus = EXIT_FAILURE;
}
_exit(istatus);
UNREACHABLE;
}
Exits the process immediately. No exit handlers are run. status is returned to the underlying system as the exit status.
Process.exit!(true)
static VALUE
rb_f_fork(VALUE obj)
{
rb_pid_t pid;
switch (pid = rb_fork_ruby(NULL)) {
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);
}
}
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.
Note that fork(2) is not available on some platforms like Windows and NetBSD 4. Therefore you should use spawn() instead of fork().
static VALUE
proc_getpgid(VALUE obj, VALUE pid)
{
rb_pid_t i;
i = getpgid(NUM2PIDT(pid));
if (i < 0) rb_sys_fail(0);
return PIDT2NUM(i);
}
Returns the process group ID for the given process id. Not available on all platforms.
Process.getpgid(Process.ppid()) #=> 25527
static VALUE
proc_getpgrp(void)
{
rb_pid_t pgrp;
#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
}
Returns the process group ID for this process. Not available on all platforms.
Process.getpgid(0) #=> 25527 Process.getpgrp #=> 25527
static VALUE
proc_getpriority(VALUE obj, VALUE which, VALUE who)
{
int prio, iwhich, iwho;
iwhich = NUM2INT(which);
iwho = NUM2INT(who);
errno = 0;
prio = getpriority(iwhich, iwho);
if (errno) rb_sys_fail(0);
return INT2FIX(prio);
}
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
static VALUE
proc_getrlimit(VALUE obj, VALUE resource)
{
struct rlimit rlim;
if (getrlimit(rlimit_resource_type(resource), &rlim) < 0) {
rb_sys_fail("getrlimit");
}
return rb_assoc_new(RLIM2NUM(rlim.rlim_cur), RLIM2NUM(rlim.rlim_max));
}
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.
static VALUE
proc_getsid(int argc, VALUE *argv)
{
rb_pid_t sid;
VALUE pid;
rb_scan_args(argc, argv, "01", &pid);
if (NIL_P(pid))
pid = INT2FIX(0);
sid = getsid(NUM2PIDT(pid));
if (sid < 0) rb_sys_fail(0);
return PIDT2NUM(sid);
}
Returns the session ID for the given process id. If not given, return current process sid. Not available on all platforms.
Process.getsid() #=> 27422 Process.getsid(0) #=> 27422 Process.getsid(Process.pid()) #=> 27422
static VALUE
proc_getgid(VALUE obj)
{
rb_gid_t gid = getgid();
return GIDT2NUM(gid);
}
Returns the (real) group ID for this process.
Process.gid #=> 500
static VALUE
proc_setgid(VALUE obj, VALUE id)
{
rb_gid_t gid;
check_gid_switch();
gid = OBJ2GID(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);
}
Sets the group ID for this process.
static VALUE
proc_getgroups(VALUE obj)
{
VALUE ary, tmp;
int i, ngroups;
rb_gid_t *groups;
ngroups = getgroups(0, NULL);
if (ngroups == -1)
rb_sys_fail(0);
groups = ALLOCV_N(rb_gid_t, tmp, ngroups);
ngroups = getgroups(ngroups, 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]));
ALLOCV_END(tmp);
return ary;
}
Get an Array of the gids of groups in the supplemental group access list for this process.
Process.groups #=> [27, 6, 10, 11]
static VALUE
proc_setgroups(VALUE obj, VALUE ary)
{
int ngroups, i;
rb_gid_t *groups;
VALUE tmp;
PREPARE_GETGRNAM;
Check_Type(ary, T_ARRAY);
ngroups = RARRAY_LENINT(ary);
if (ngroups > maxgroups())
rb_raise(rb_eArgError, "too many groups, %d max", maxgroups());
groups = ALLOCV_N(rb_gid_t, tmp, ngroups);
for (i = 0; i < ngroups; i++) {
VALUE g = RARRAY_AREF(ary, i);
groups[i] = OBJ2GID1(g);
}
FINISH_GETGRNAM;
if (setgroups(ngroups, groups) == -1) /* ngroups <= maxgroups */
rb_sys_fail(0);
ALLOCV_END(tmp);
return proc_getgroups(obj);
}
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]
static VALUE
proc_initgroups(VALUE obj, VALUE uname, VALUE base_grp)
{
if (initgroups(StringValuePtr(uname), OBJ2GID(base_grp)) != 0) {
rb_sys_fail(0);
}
return proc_getgroups(obj);
}
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]
VALUE
rb_f_kill(int argc, const VALUE *argv)
{
#ifndef HAVE_KILLPG
#define killpg(pg, sig) kill(-(pg), (sig))
#endif
int negative = 0;
int sig;
int i;
VALUE str;
const char *s;
rb_check_arity(argc, 2, UNLIMITED_ARGUMENTS);
switch (TYPE(argv[0])) {
case T_FIXNUM:
sig = FIX2INT(argv[0]);
break;
case T_SYMBOL:
str = rb_sym2str(argv[0]);
goto str_signal;
case T_STRING:
str = argv[0];
str_signal:
s = RSTRING_PTR(str);
if (s[0] == '-') {
negative++;
s++;
}
if (strncmp(signame_prefix, s, sizeof(signame_prefix)) == 0)
s += 3;
if ((sig = signm2signo(s)) == 0) {
long ofs = s - RSTRING_PTR(str);
if (ofs) str = rb_str_subseq(str, ofs, RSTRING_LEN(str)-ofs);
rb_raise(rb_eArgError, "unsupported name `SIG%"PRIsVALUE"'", str);
}
if (negative)
sig = -sig;
break;
default:
str = rb_check_string_type(argv[0]);
if (!NIL_P(str)) {
goto str_signal;
}
rb_raise(rb_eArgError, "bad signal type %s",
rb_obj_classname(argv[0]));
break;
}
if (argc <= 1) return INT2FIX(0);
if (sig < 0) {
sig = -sig;
for (i=1; i<argc; i++) {
if (killpg(NUM2PIDT(argv[i]), sig) < 0)
rb_sys_fail(0);
}
}
else {
const rb_pid_t self = (GET_THREAD() == GET_VM()->main_thread) ? getpid() : -1;
int wakeup = 0;
for (i=1; i<argc; i++) {
rb_pid_t pid = NUM2PIDT(argv[i]);
if ((sig != 0) && (self != -1) && (pid == self)) {
int t;
/*
* When target pid is self, many caller assume signal will be
* delivered immediately and synchronously.
*/
switch (sig) {
case SIGSEGV:
#ifdef SIGBUS
case SIGBUS:
#endif
#ifdef SIGKILL
case SIGKILL:
#endif
#ifdef SIGSTOP
case SIGSTOP:
#endif
ruby_kill(pid, sig);
break;
default:
t = signal_ignored(sig);
if (t) {
if (t < 0 && kill(pid, sig))
rb_sys_fail(0);
break;
}
signal_enque(sig);
wakeup = 1;
}
}
else if (kill(pid, sig) < 0) {
rb_sys_fail(0);
}
}
if (wakeup) {
rb_threadptr_check_signal(GET_VM()->main_thread);
}
}
rb_thread_execute_interrupts(rb_thread_current());
return INT2FIX(i-1);
}
Sends the given signal to the specified process id(s) if pid is positive. If pid is zero signal is sent to all processes whose group ID is equal to the group ID of the process. 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. The keys and values of Signal.list are known signal names and numbers, respectively.
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.
static VALUE
proc_getmaxgroups(VALUE obj)
{
return INT2FIX(maxgroups());
}
Returns the maximum number of gids allowed in the supplemental group access list.
Process.maxgroups #=> 32
static VALUE
proc_setmaxgroups(VALUE obj, VALUE val)
{
int ngroups = FIX2INT(val);
int ngroups_max = get_sc_ngroups_max();
if (ngroups <= 0)
rb_raise(rb_eArgError, "maxgroups %d shold be positive", ngroups);
if (ngroups > RB_MAX_GROUPS)
ngroups = RB_MAX_GROUPS;
if (ngroups_max > 0 && ngroups > ngroups_max)
ngroups = ngroups_max;
_maxgroups = ngroups;
return INT2FIX(_maxgroups);
}
Sets the maximum number of gids allowed in the supplemental group access list.
static VALUE
get_pid(void)
{
return PIDT2NUM(getpid());
}
Returns the process id of this process. Not available on all platforms.
Process.pid #=> 27415
static VALUE
get_ppid(void)
{
return PIDT2NUM(getppid());
}
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
static VALUE
proc_setpgid(VALUE obj, VALUE pid, VALUE pgrp)
{
rb_pid_t ipid, ipgrp;
ipid = NUM2PIDT(pid);
ipgrp = NUM2PIDT(pgrp);
if (setpgid(ipid, ipgrp) < 0) rb_sys_fail(0);
return INT2FIX(0);
}
Sets the process group ID of pid (0 indicates this process) to integer. Not available on all platforms.
static VALUE
proc_setpgrp(void)
{
/* 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);
}
Equivalent to setpgid(0,0). Not available on all platforms.
static VALUE
proc_setpriority(VALUE obj, VALUE which, VALUE who, VALUE prio)
{
int iwhich, iwho, iprio;
iwhich = NUM2INT(which);
iwho = NUM2INT(who);
iprio = NUM2INT(prio);
if (setpriority(iwhich, iwho, iprio) < 0)
rb_sys_fail(0);
return INT2FIX(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
static VALUE
proc_setproctitle(VALUE process, VALUE title)
{
StringValue(title);
setproctitle("%.*s", RSTRING_LENINT(title), RSTRING_PTR(title));
return title;
}
Sets the process title that appears on the ps(1) command. Not necessarily effective on all platforms. No exception will be raised regardless of the result, nor will NotImplementedError be raised even if the platform does not support the feature.
Calling this method does not affect the value of $0.
Process.setproctitle('myapp: worker #%d' % worker_id)
This method first appeared in Ruby 2.1 to serve as a global variable free means to change the process title.
Process.setrlimit(resource, cur_limit, max_limit) → nil
Process.setrlimit(resource, cur_limit) → nil
static VALUE
proc_setrlimit(int argc, VALUE *argv, VALUE obj)
{
VALUE resource, rlim_cur, rlim_max;
struct rlimit rlim;
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;
}
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.
- AS
-
total available memory (bytes) (SUSv3, NetBSD, FreeBSD, OpenBSD but 4.4BSD-Lite)
- CORE
-
core size (bytes) (SUSv3)
- CPU
-
CPU time (seconds) (SUSv3)
- DATA
-
data segment (bytes) (SUSv3)
- FSIZE
-
file size (bytes) (SUSv3)
- MEMLOCK
-
total size for mlock(2) (bytes) (4.4BSD, GNU/Linux)
- MSGQUEUE
-
allocation for POSIX message queues (bytes) (GNU/Linux)
- NICE
-
ceiling on process’s nice(2) value (number) (GNU/Linux)
- NOFILE
-
file descriptors (number) (SUSv3)
- NPROC
-
number of processes for the user (number) (4.4BSD, GNU/Linux)
RSS-
resident memory size (bytes) (4.2BSD, GNU/Linux)
- RTPRIO
-
ceiling on the process’s real-time priority (number) (GNU/Linux)
- RTTIME
-
CPU time for real-time process (us) (GNU/Linux)
- SBSIZE
-
all socket buffers (bytes) (NetBSD, FreeBSD)
- SIGPENDING
-
number of queued signals allowed (signals) (GNU/Linux)
- STACK
-
stack size (bytes) (SUSv3)
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 raises 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_setsid(void)
{
rb_pid_t pid;
pid = setsid();
if (pid < 0) rb_sys_fail(0);
return PIDT2NUM(pid);
}
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
rb_f_spawn(int argc, VALUE *argv)
{
rb_pid_t pid;
char errmsg[CHILD_ERRMSG_BUFLEN] = { '\0' };
VALUE execarg_obj, fail_str;
struct rb_execarg *eargp;
execarg_obj = rb_execarg_new(argc, argv, TRUE);
eargp = rb_execarg_get(execarg_obj);
fail_str = eargp->use_shell ? eargp->invoke.sh.shell_script : eargp->invoke.cmd.command_name;
pid = rb_execarg_spawn(execarg_obj, errmsg, sizeof(errmsg));
if (pid == -1) {
int err = errno;
rb_exec_fail(eargp, err, errmsg);
RB_GC_GUARD(execarg_obj);
rb_syserr_fail_str(err, fail_str);
}
#if defined(HAVE_WORKING_FORK) || defined(HAVE_SPAWNV)
return PIDT2NUM(pid);
#else
return Qnil;
#endif
}
spawn executes specified command and return its pid.
pid = spawn("tar xf ruby-2.0.0-p195.tar.bz2") Process.wait pid pid = spawn(RbConfig.ruby, "-eputs'Hello, world!'") Process.wait pid
This method is similar to Kernel#system but it doesn’t wait for the command to finish.
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
the keys and the values except for +nil+ must be strings.
command...:
commandline : command line string which is passed to the standard shell
cmdname, arg1, ... : command name and one or more arguments (This form does not use the shell. See below for caveats.)
[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 the specified process group
:pgroup => nil : don't change the process group (default)
create new process group: Windows only
:new_pgroup => true : the new process is the root process of a new process group
:new_pgroup => false : don't create a new process group (default)
resource limit: resourcename is core, cpu, data, etc. See Process.setrlimit.
:rlimit_resourcename => limit
:rlimit_resourcename => [cur_limit, max_limit]
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 => true : don't inherit
current directory:
:chdir => str
The 'cmdname, arg1, ...' form does not use the shell. However,
on different OSes, different things are provided as built-in
commands. An example of this is 'echo', which is a built-in
on Windows, but is a normal program on Linux and Mac OS X.
This means that `Process.spawn 'echo', '%Path%'` will display
the contents of the `%Path%` environment variable on Windows,
but `Process.spawn 'echo', '$PATH'` prints the literal '$PATH'.
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, create new 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, a positive integer, or nil. true and zero cause the process to be a process leader of a new process group. A non-zero positive integer causes the process to join the provided process group. The default value, nil, causes the process to remain in the same process group.
pid = spawn(command, :pgroup=>true) # process leader pid = spawn(command, :pgroup=>10) # belongs to the process group 10
The :new_pgroup key in options specifies to pass CREATE_NEW_PROCESS_GROUP flag to CreateProcessW() that is Windows API. This option is only for Windows. true means the new process is the root process of the new process group. The new process has CTRL+C disabled. This flag is necessary for Process.kill(:SIGINT, pid) on the subprocess. :new_pgroup is false by default.
pid = spawn(command, :new_pgroup=>true) # new process group pid = spawn(command, :new_pgroup=>false) # same process group
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 :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, [:out, :err]=>"/dev/null") # write mode pid = spawn(command, 3=>"/dev/null") # read mode
For stdout and stderr (and combination of them), 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 differ 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"
The :chdir key in options specifies the current directory.
pid = spawn(command, :chdir=>"/var/tmp")
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.
Note that fds which close-on-exec flag is already set are closed regardless of :close_others option.
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.
VALUE
rb_proc_times(VALUE obj)
{
const double hertz = get_clk_tck();
struct tms buf;
VALUE utime, stime, cutime, cstime, ret;
times(&buf);
utime = DBL2NUM(buf.tms_utime / hertz);
stime = DBL2NUM(buf.tms_stime / hertz);
cutime = DBL2NUM(buf.tms_cutime / hertz);
cstime = DBL2NUM(buf.tms_cstime / hertz);
ret = rb_struct_new(rb_cProcessTms, utime, stime, cutime, cstime);
RB_GC_GUARD(utime);
RB_GC_GUARD(stime);
RB_GC_GUARD(cutime);
RB_GC_GUARD(cstime);
return ret;
}
Returns a Tms structure (see Process::Tms) that contains user and system CPU times for this process, and also for children processes.
t = Process.times [ t.utime, t.stime, t.cutime, t.cstime ] #=> [0.0, 0.02, 0.00, 0.00]
static VALUE
proc_getuid(VALUE obj)
{
rb_uid_t uid = getuid();
return UIDT2NUM(uid);
}
Returns the (real) user ID of this process.
Process.uid #=> 501
static VALUE
proc_setuid(VALUE obj, VALUE id)
{
rb_uid_t uid;
check_uid_switch();
uid = OBJ2UID(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;
}
Sets the (user) user ID for this process. Not available on all platforms.
static VALUE
proc_wait(int argc, VALUE *argv)
{
VALUE vpid, vflags;
rb_pid_t pid;
int flags, status;
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);
}
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 SystemCallError 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_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());
}
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 SystemCallError if there are no child processes.
Process.fork { exit 99 } #=> 27437 pid, status = Process.wait2 pid #=> 27437 status.exitstatus #=> 99
static VALUE
proc_waitall(void)
{
VALUE result;
rb_pid_t pid;
int status;
result = rb_ary_new();
rb_last_status_clear();
for (pid = -1;;) {
pid = rb_waitpid(-1, &status, 0);
if (pid == -1) {
int e = errno;
if (e == ECHILD)
break;
rb_syserr_fail(e, 0);
}
rb_ary_push(result, rb_assoc_new(PIDT2NUM(pid), rb_last_status_get()));
}
return result;
}
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:
[[30982, #<Process::Status: pid 30982 exit 0>], [30979, #<Process::Status: pid 30979 exit 1>], [30976, #<Process::Status: pid 30976 exit 2>]]
static VALUE
proc_wait(int argc, VALUE *argv)
{
VALUE vpid, vflags;
rb_pid_t pid;
int flags, status;
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);
}
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 SystemCallError 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_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());
}
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 SystemCallError if there are no child processes.
Process.fork { exit 99 } #=> 27437 pid, status = Process.wait2 pid #=> 27437 status.exitstatus #=> 99