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Class: Process::Status

Relationships & Source Files
Inherits: Object
Defined in: process.c,
process.c

Overview

Status encapsulates the information on the status of a running or terminated system process. The built-in variable $? is either nil or a 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 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.

Instance Attribute Summary

Instance Method Summary

Instance Attribute Details

#coredump?Boolean (readonly)

Returns true if stat generated a coredump when it terminated. Not available on all platforms.

[ GitHub ]

  
# File 'process.c', line 892

static VALUE
pst_wcoredump(VALUE st)
{
#ifdef WCOREDUMP
    int status = PST2INT(st);

    if (WCOREDUMP(status))
	return Qtrue;
    else
	return Qfalse;
#else
    return Qfalse;
#endif
}

#exited?Boolean (readonly)

Returns true if stat exited normally (for example using an exit() call or finishing the program).

[ GitHub ]

  
# File 'process.c', line 824

static VALUE
pst_wifexited(VALUE st)
{
    int status = PST2INT(st);

    if (WIFEXITED(status))
	return Qtrue;
    else
	return Qfalse;
}

#signaled?Boolean (readonly)

Returns true if stat terminated because of an uncaught signal.

[ GitHub ]

  
# File 'process.c', line 783

static VALUE
pst_wifsignaled(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSIGNALED(status))
	return Qtrue;
    else
	return Qfalse;
}

#stopped?Boolean (readonly)

Returns true if this process is stopped. This is only returned if the corresponding Process#wait call had the WUNTRACED flag set.

[ GitHub ]

  
# File 'process.c', line 744

static VALUE
pst_wifstopped(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSTOPPED(status))
	return Qtrue;
    else
	return Qfalse;
}

#success?Boolean (readonly)

Returns true if stat is successful, false if not. Returns nil if #exited? is not true.

[ GitHub ]

  
# File 'process.c', line 873

static VALUE
pst_success_p(VALUE st)
{
    int status = PST2INT(st);

    if (!WIFEXITED(status))
	return Qnil;
    return WEXITSTATUS(status) == EXIT_SUCCESS ? Qtrue : Qfalse;
}

Instance Method Details

#&(num) ⇒ Integer

Logical AND of the bits in stat with num.

fork { exit 0x37 }
Process.wait
sprintf('%04x', $?.to_i)       #=> "3700"
sprintf('%04x', $? & 0x1e00)   #=> "1600"
[ GitHub ]

  
# File 'process.c', line 705

static VALUE
pst_bitand(VALUE st1, VALUE st2)
{
    int status = PST2INT(st1) & NUM2INT(st2);

    return INT2NUM(status);
}

#==(other) ⇒ Boolean

Returns true if the integer value of stat equals other.

[ GitHub ]

  
# File 'process.c', line 685

static VALUE
pst_equal(VALUE st1, VALUE st2)
{
    if (st1 == st2) return Qtrue;
    return rb_equal(pst_to_i(st1), st2);
}

#>>(num) ⇒ Integer

Shift the bits in stat right num places.

fork { exit 99 }   #=> 26563
Process.wait       #=> 26563
$?.to_i            #=> 25344
$? >> 8            #=> 99
[ GitHub ]

  
# File 'process.c', line 726

static VALUE
pst_rshift(VALUE st1, VALUE st2)
{
    int status = PST2INT(st1) >> NUM2INT(st2);

    return INT2NUM(status);
}

#exitstatusInteger?

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
[ GitHub ]

  
# File 'process.c', line 854

static VALUE
pst_wexitstatus(VALUE st)
{
    int status = PST2INT(st);

    if (WIFEXITED(status))
	return INT2NUM(WEXITSTATUS(status));
    return Qnil;
}

#inspectString

Override the inspection method.

system("false")
p $?.inspect #=> "#<Process::Status: pid 12861 exit 1>"
[ GitHub ]

  
# File 'process.c', line 656

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;
}

#pidInteger

Returns the process ID that this status object represents.

fork { exit }   #=> 26569
Process.wait    #=> 26569
$?.pid          #=> 26569
[ GitHub ]

  
# File 'process.c', line 568

static VALUE
pst_pid(VALUE st)
{
    return rb_attr_get(st, id_pid);
}

#stopsigInteger?

Returns the number of the signal that caused stat to stop (or nil if self is not stopped).

[ GitHub ]

  
# File 'process.c', line 764

static VALUE
pst_wstopsig(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSTOPPED(status))
	return INT2NUM(WSTOPSIG(status));
    return Qnil;
}

#termsigInteger?

Returns the number of the signal that caused stat to terminate (or nil if self was not terminated by an uncaught signal).

[ GitHub ]

  
# File 'process.c', line 804

static VALUE
pst_wtermsig(VALUE st)
{
    int status = PST2INT(st);

    if (WIFSIGNALED(status))
	return INT2NUM(WTERMSIG(status));
    return Qnil;
}

#to_iInteger #to_intInteger

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"
[ GitHub ]

  
# File 'process.c', line 549

static VALUE
pst_to_i(VALUE st)
{
    return rb_ivar_get(st, id_status);
}

#to_sString

Show pid and exit status as a string.

system("false")
p $?.to_s         #=> "pid 12766 exit 1"
[ GitHub ]

  
# File 'process.c', line 629

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;
}