According to POSIX, exit status must be 127 if the requested utility was not

found, 126 if the execvp() failed for any other reason.

Similar to rev. 1.6 to src/usr.bin/env/env.c

Reviewed by:	mike

usr.bin/nice/nice.1

@@ -72,10 +72,6 @@ super-user.
 Negative numbers are expressed as
 .Fl - Ns Ar number .
 .Pp
-The returned exit status is the exit value from the
-command executed by
-.Nm .
-.Pp
 Some shells may provide a builtin
 .Nm
 command which is similar or identical to this utility.
@@ -96,6 +92,20 @@ Execute command
 .Sq date
 at priority -19 assuming the priority of the
 shell is 0 and you are the super-user.
+.Sh DIAGNOSTICS
+If
+.Ar command
+is invoked, the exit status of
+.Nm
+is the exit status of
+.Ar command .
+.Pp
+An exit status of 126 indicates
+.Ar command
+was found, but could not be executed.
+An exit status of 127 indicates
+.Ar command
+could not be found.
 .Sh SEE ALSO
 .Xr builtin 1 ,
 .Xr csh 1 ,

usr.bin/nice/nice.c

@@ -90,7 +90,7 @@ main(argc, argv)
 	if (setpriority(PRIO_PROCESS, 0, niceness))
 		err(1, "setpriority");
 	execvp(argv[1], &argv[1]);
-	err(1, "%s", argv[1]);
+	err(errno == ENOENT ? 127 : 126, "%s", argv[1]);
 }
 
 void