Support the SUSv3 -n option and the "--" end of options marker.

Replace "command" with "utility" in the manual page & source to be more
consistent with the terminology used in the standard, and to hint that
shell builtin commands won't work.

Submitted by:	Peter Avalos <pavalos@theshell.com> (partially)
Approved by:	mike

2 files changed, 61 insertions, 51 deletions

diff --git a/usr.bin/nice/nice.1 b/usr.bin/nice/nice.1
index 3ed43a3..9948e3a 100644
--- a/usr.bin/nice/nice.1
+++ b/usr.bin/nice/nice.1
@@ -37,40 +37,26 @@
 .Os
 .Sh NAME
 .Nm nice
-.Nd execute a command at a low scheduling priority
+.Nd execute a utility at an altered scheduling priority
 .Sh SYNOPSIS
 .Nm
-.Op Fl Ns Ar number
-.Ar command
-.Op Ar arguments
+.Op Fl n Ar increment
+.Ar utility
+.Op Ar argument ...
 .Sh DESCRIPTION
 The
 .Nm
 utility runs
-.Ar command
-at a low priority.
-(Think of low and slow).
-If
-.Fl Ns Ar number
-is not given,
-.Nm
-assumes the value 10.
-The priority is a value in the range -20 to 20.
-The default priority is 0, priority 20 is the lowest possible.
-The
-.Nm
-utility will execute
-.Ar command
-at priority
-.Ar number
-relative to the priority
-of
-.Nm .
-Higher priorities than the
-current process priority can only requested by the
-super-user.
-Negative numbers are expressed as
-.Fl - Ns Ar number .
+.Ar utility
+at an altered scheduling priority, by incrementing its
+.Dq nice
+value by the specified
+.Ar increment ,
+or a default value of 10.
+The lower the nice value of a process, the higher its scheduling priority.
+.Pp
+The superuser may specify a negative increment in order to run a utility
+with a higher scheduling prority.
 .Pp
 Some shells may provide a builtin
 .Nm
@@ -79,32 +65,32 @@ Consult the
 .Xr builtin 1
 manual page.
 .Sh EXAMPLES
-$ nice -5 date
+$ nice -n 5 date
 .Pp
-Execute command
+Execute utility
 .Sq date
 at priority 5 assuming the priority of the
 shell is 0.
 .Pp
-# nice -16 nice --35 date
+# nice -n 16 nice -n -35 date
 .Pp
-Execute command
+Execute utility
 .Sq date
 at priority -19 assuming the priority of the
 shell is 0 and you are the super-user.
 .Sh DIAGNOSTICS
 If
-.Ar command
+.Ar utility
 is invoked, the exit status of
 .Nm
 is the exit status of
-.Ar command .
+.Ar utility .
 .Pp
 An exit status of 126 indicates
-.Ar command
+.Ar utility
 was found, but could not be executed.
 An exit status of 127 indicates
-.Ar command
+.Ar utility
 could not be found.
 .Sh SEE ALSO
 .Xr builtin 1 ,
@@ -114,8 +100,17 @@ could not be found.
 .Xr getpriority 2 ,
 .Xr setpriority 2 ,
 .Xr renice 8
+.Sh COMPATIBILITY
+The traditional
+.Fl Ns Ar increment
+option has been deprecated but is still supported.
+.Sh STANDARDS
+The
+.Nm
+utility conforms to
+.St -p1003.1-2001 .
 .Sh HISTORY
 A
 .Nm
-command appeared in
+utility appeared in
 .At v6 .
diff --git a/usr.bin/nice/nice.c b/usr.bin/nice/nice.c
index d9d91c4..13634a1 100644
--- a/usr.bin/nice/nice.c
+++ b/usr.bin/nice/nice.c
@@ -53,6 +53,7 @@ __FBSDID("$FreeBSD$");
 #include <ctype.h>
 #include <err.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -67,35 +68,49 @@ main(argc, argv)
 	int argc;
 	char *argv[];
 {
-	int niceness = DEFNICE;
+	long niceness = DEFNICE;
+	int ch;
+	char *ep;
 
-	if (argc < 2)
-		usage();
+	/* Obsolescent syntax: -number, --number */
+	if (argc >= 2 && argv[1][0] == '-' && (argv[1][1] == '-' ||
+	    isdigit((unsigned char)argv[1][1])) && strcmp(argv[1], "--") != 0)
+		if (asprintf(&argv[1], "-n%s", argv[1] + 1) < 0)
+			err(1, "asprintf");
 
-	if (argv[1][0] == '-') {
-		if (argv[1][1] == '-' || isdigit(argv[1][1])) {
-			niceness = atoi(argv[1] + 1);
-			++argv;
-		} else
-			errx(1, "illegal option -- %s", argv[1]);
+	while ((ch = getopt(argc, argv, "n:")) != -1) {
+		switch (ch) {
+		case 'n':
+			errno = 0;
+			niceness = strtol(optarg, &ep, 10);
+			if (ep == optarg || *ep != '\0' || errno ||
+			    niceness < INT_MIN || niceness > INT_MAX)
+				errx(1, "%s: invalid nice value", optarg);
+			break;
+		default:
+			usage();
+		}
 	}
+	argc -= optind;
+	argv += optind;
 
-	if (argv[1] == NULL)
+	if (argc == 0)
 		usage();
 
 	errno = 0;
 	niceness += getpriority(PRIO_PROCESS, 0);
 	if (errno)
 		err(1, "getpriority");
-	if (setpriority(PRIO_PROCESS, 0, niceness))
+	if (setpriority(PRIO_PROCESS, 0, (int)niceness))
 		err(1, "setpriority");
-	execvp(argv[1], &argv[1]);
-	err(errno == ENOENT ? 127 : 126, "%s", argv[1]);
+	execvp(*argv, argv);
+	err(errno == ENOENT ? 127 : 126, "%s", *argv);
 }
 
 void
 usage()
 {
-	(void)fprintf(stderr, "usage: nice [-number] command [arguments]\n");
+
+	(void)fprintf(stderr, "usage: nice [-n incr] utility [arguments]\n");
 	exit(1);
 }