In Files

  • process.c

Process::Status

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.

Public Instance Methods

stat & num => fixnum click to toggle source

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

    return INT2NUM(status);
}
            
stat == other => true or false click to toggle source

Returns true if the integer value of stat equals other.

 
               static VALUE
pst_equal(st1, st2)
    VALUE st1, st2;
{
    if (st1 == st2) return Qtrue;
    return rb_equal(pst_to_i(st1), st2);
}
            
stat >> num => fixnum click to toggle source

Shift the bits in stat right num places.

fork { exit 99 }   #=> 26563
Process.wait       #=> 26563
$?.to_i            #=> 25344
$? >> 8            #=> 99
 
               static VALUE
pst_rshift(st1, st2)
    VALUE st1, st2;
{
    int status = NUM2INT(st1) >> NUM2INT(st2);

    return INT2NUM(status);
}
            
coredump? => true or false click to toggle source

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

 
               static VALUE
pst_wcoredump(st)
    VALUE st;
{
#ifdef WCOREDUMP
    int status = NUM2INT(st);

    if (WCOREDUMP(status))
        return Qtrue;
    else
        return Qfalse;
#else
    return Qfalse;
#endif
}
            
exited? => true or false click to toggle source

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

 
               static VALUE
pst_wifexited(st)
    VALUE st;
{
    int status = NUM2INT(st);

    if (WIFEXITED(status))
        return Qtrue;
    else
        return Qfalse;
}
            
exitstatus => fixnum or nil click to toggle source

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(st)
    VALUE st;
{
    int status = NUM2INT(st);

    if (WIFEXITED(status))
        return INT2NUM(WEXITSTATUS(status));
    return Qnil;
}
            
inspect => string click to toggle source

Override the inspection method.

 
               static VALUE
pst_inspect(st)
    VALUE st;
{
    VALUE pid;
    int status;
    VALUE str;
    char buf[256];

    pid = pst_pid(st);
    status = NUM2INT(st);

    snprintf(buf, sizeof(buf), "#<%s: pid=%ld", rb_class2name(CLASS_OF(st)), NUM2LONG(pid));
    str = rb_str_new2(buf);
    if (WIFSTOPPED(status)) {
        int stopsig = WSTOPSIG(status);
        const char *signame = ruby_signal_name(stopsig);
        if (signame) {
            snprintf(buf, sizeof(buf), ",stopped(SIG%s=%d)", signame, stopsig);
        }
        else {
            snprintf(buf, sizeof(buf), ",stopped(%d)", stopsig);
        }
        rb_str_cat2(str, buf);
    }
    if (WIFSIGNALED(status)) {
        int termsig = WTERMSIG(status);
        const char *signame = ruby_signal_name(termsig);
        if (signame) {
            snprintf(buf, sizeof(buf), ",signaled(SIG%s=%d)", signame, termsig);
        }
        else {
            snprintf(buf, sizeof(buf), ",signaled(%d)", termsig);
        }
        rb_str_cat2(str, buf);
    }
    if (WIFEXITED(status)) {
        snprintf(buf, sizeof(buf), ",exited(%d)", WEXITSTATUS(status));
        rb_str_cat2(str, buf);
    }
#ifdef WCOREDUMP
    if (WCOREDUMP(status)) {
        rb_str_cat2(str, ",coredumped");
    }
#endif
    rb_str_cat2(str, ">");
    return str;
}
            
pid => fixnum click to toggle source

Returns the process ID that this status object represents.

fork { exit }   #=> 26569
Process.wait    #=> 26569
$?.pid          #=> 26569
 
               static VALUE
pst_pid(st)
    VALUE st;
{
    return rb_iv_get(st, "pid");
}
            
signaled? => true or false click to toggle source

Returns true if stat terminated because of an uncaught signal.

 
               static VALUE
pst_wifsignaled(st)
    VALUE st;
{
    int status = NUM2INT(st);

    if (WIFSIGNALED(status))
        return Qtrue;
    else
        return Qfalse;
}
            
stopped? => true or false click to toggle source

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(st)
    VALUE st;
{
    int status = NUM2INT(st);

    if (WIFSTOPPED(status))
        return Qtrue;
    else
        return Qfalse;
}
            
stopsig => fixnum or nil click to toggle source

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

 
               static VALUE
pst_wstopsig(st)
    VALUE st;
{
    int status = NUM2INT(st);

    if (WIFSTOPPED(status))
        return INT2NUM(WSTOPSIG(status));
    return Qnil;
}
            
success? => true, false or nil click to toggle source

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

 
               static VALUE
pst_success_p(st)
    VALUE st;
{
    int status = NUM2INT(st);

    if (!WIFEXITED(status))
        return Qnil;
    return WEXITSTATUS(status) == EXIT_SUCCESS ? Qtrue : Qfalse;
}
            
termsig => fixnum or nil click to toggle source

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(st)
    VALUE st;
{
    int status = NUM2INT(st);

    if (WIFSIGNALED(status))
        return INT2NUM(WTERMSIG(status));
    return Qnil;
}
            
to_i => fixnum click to toggle source
to_int => fixnum

Returns the bits in stat as a Fixnum. 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(st)
    VALUE st;
{
    return rb_iv_get(st, "status");
}
            
to_int => fixnum click to toggle source

Returns the bits in stat as a Fixnum. 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(st)
    VALUE st;
{
    return rb_iv_get(st, "status");
}
            
to_s => string click to toggle source

Equivalent to stat.to_i.to_s.

 
               static VALUE
pst_to_s(st)
    VALUE st;
{
    return rb_fix2str(pst_to_i(st), 10);
}
            

Commenting is here to help enhance the documentation. For example, code samples, or clarification of the documentation.

If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.

If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.

If you want to help improve the Ruby documentation, please visit Documenting-ruby.org.

blog comments powered by Disqus