Process::Status
encapsulates the information on the status of a running or terminated system process. The built-in variable $?
is either nil
or a Process::Status
object.
fork { exit 99 } #=> 26557 Process.wait #=> 26557 $?.class #=> Process::Status $?.to_i #=> 25344 $? >> 8 #=> 99 $?.stopped? #=> false $?.exited? #=> true $?.exitstatus #=> 99
Posix systems record information on processes using a 16-bit integer. The lower bits record the process status (stopped, exited, signaled) and the upper bits possibly contain additional information (for example the program's return code in the case of exited processes). Pre Ruby 1.8, these bits were exposed directly to the Ruby program. Ruby now encapsulates these in a Process::Status
object. To maximize compatibility, however, these objects retain a bit-oriented interface. In the descriptions that follow, when we talk about the integer value of stat, we're referring to this 16 bit value.
Logical AND of the bits in stat with num.
fork { exit 0x37 } Process.wait sprintf('%04x', $?.to_i) #=> "3700" sprintf('%04x', $? & 0x1e00) #=> "1600"
static VALUE pst_bitand(VALUE st1, VALUE st2) { int status = PST2INT(st1) & NUM2INT(st2); return INT2NUM(status); }
Returns true
if the integer value of stat equals other.
static VALUE pst_equal(VALUE st1, VALUE st2) { if (st1 == st2) return Qtrue; return rb_equal(pst_to_i(st1), st2); }
Shift the bits in stat right num places.
fork { exit 99 } #=> 26563 Process.wait #=> 26563 $?.to_i #=> 25344 $? >> 8 #=> 99
static VALUE pst_rshift(VALUE st1, VALUE st2) { int status = PST2INT(st1) >> NUM2INT(st2); return INT2NUM(status); }
Returns true
if stat generated a coredump when it terminated. Not available on all platforms.
static VALUE pst_wcoredump(VALUE st) { #ifdef WCOREDUMP int status = PST2INT(st); if (WCOREDUMP(status)) return Qtrue; else return Qfalse; #else return Qfalse; #endif }
Returns true
if stat exited normally (for example using an exit()
call or finishing the program).
static VALUE pst_wifexited(VALUE st) { int status = PST2INT(st); if (WIFEXITED(status)) return Qtrue; else return Qfalse; }
Returns the least significant eight bits of the return code of stat. Only available if exited?
is true
.
fork { } #=> 26572 Process.wait #=> 26572 $?.exited? #=> true $?.exitstatus #=> 0 fork { exit 99 } #=> 26573 Process.wait #=> 26573 $?.exited? #=> true $?.exitstatus #=> 99
static VALUE pst_wexitstatus(VALUE st) { int status = PST2INT(st); if (WIFEXITED(status)) return INT2NUM(WEXITSTATUS(status)); return Qnil; }
Override the inspection method.
system("false") p $?.inspect #=> "#<Process::Status: pid 12861 exit 1>"
static VALUE pst_inspect(VALUE st) { rb_pid_t pid; int status; VALUE vpid, str; vpid = pst_pid(st); if (NIL_P(vpid)) { return rb_sprintf("#<%s: uninitialized>", rb_class2name(CLASS_OF(st))); } pid = NUM2PIDT(vpid); status = PST2INT(st); str = rb_sprintf("#<%s: ", rb_class2name(CLASS_OF(st))); pst_message(str, pid, status); rb_str_cat2(str, ">"); return str; }
Returns the process ID that this status object represents.
fork { exit } #=> 26569 Process.wait #=> 26569 $?.pid #=> 26569
static VALUE pst_pid(VALUE st) { return rb_attr_get(st, id_pid); }
Returns true
if stat terminated because of an uncaught signal.
static VALUE pst_wifsignaled(VALUE st) { int status = PST2INT(st); if (WIFSIGNALED(status)) return Qtrue; else return Qfalse; }
Returns true
if this process is stopped. This is only returned if the corresponding wait
call had the WUNTRACED
flag set.
static VALUE pst_wifstopped(VALUE st) { int status = PST2INT(st); if (WIFSTOPPED(status)) return Qtrue; else return Qfalse; }
Returns the number of the signal that caused stat to stop (or nil
if self is not stopped).
static VALUE pst_wstopsig(VALUE st) { int status = PST2INT(st); if (WIFSTOPPED(status)) return INT2NUM(WSTOPSIG(status)); return Qnil; }
Returns true
if stat is successful, false
if not. Returns nil
if exited?
is not true
.
static VALUE pst_success_p(VALUE st) { int status = PST2INT(st); if (!WIFEXITED(status)) return Qnil; return WEXITSTATUS(status) == EXIT_SUCCESS ? Qtrue : Qfalse; }
Returns the number of the signal that caused stat to terminate (or nil
if self was not terminated by an uncaught signal).
static VALUE pst_wtermsig(VALUE st) { int status = PST2INT(st); if (WIFSIGNALED(status)) return INT2NUM(WTERMSIG(status)); return Qnil; }
Returns the bits in stat as a Integer
. Poking around in these bits is platform dependent.
fork { exit 0xab } #=> 26566 Process.wait #=> 26566 sprintf('%04x', $?.to_i) #=> "ab00"
static VALUE pst_to_i(VALUE st) { return rb_ivar_get(st, id_status); }
Show pid and exit status as a string.
system("false") p $?.to_s #=> "pid 12766 exit 1"
static VALUE pst_to_s(VALUE st) { rb_pid_t pid; int status; VALUE str; pid = NUM2PIDT(pst_pid(st)); status = PST2INT(st); str = rb_str_buf_new(0); pst_message(str, pid, status); return str; }