* process.c (rb_f_system): returns nil on execution failure.

[ruby-core:13715]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13990 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Nov 21 03:12:50 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* process.c (rb_f_system): returns nil on execution failure.
+	  [ruby-core:13715]
+
 Wed Nov 21 01:04:12 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* object.c (nil_plus): remove unused function.  [ruby-core:13737]

process.c

@@ -1758,10 +1758,11 @@ rb_spawn(int argc, VALUE *argv)
  *  call-seq:
  *     system(cmd [, arg, ...])    => true or false
  *
- *  Executes _cmd_ in a subshell, returning +true+ if the command ran
- *  successfully, +false+ otherwise. An error status is available in
+ *  Executes _cmd_ in a subshell, returning +true+ if the command
+ *  gives zero exit status, +false+ for non zero exit status. Returns
+ *  +nil+ if command execution fails.  An error status is available in
  *  <code>$?</code>. The arguments are processed in the same way as
- *  for <code>Kernel::exec</code>, and raises same exceptions as it.
+ *  for <code>Kernel::exec</code>.
  *
  *     system("echo *")
  *     system("echo", "*")
@@ -1795,7 +1796,7 @@ rb_f_system(int argc, VALUE *argv)
     signal(SIGCHLD, chfunc);
 #endif
     if (status < 0) {
-	rb_sys_fail(RSTRING_PTR(argv[0]));
+	return Qnil;
     }
     status = NUM2INT(rb_last_status_get());
     if (status == EXIT_SUCCESS) return Qtrue;