From f31df7b5941dbdc6e6bb5151595ec5f3fe75b0b9 Mon Sep 17 00:00:00 2001
From: Aaron LI <aly@aaronly.me>
Date: Fri, 19 Jun 2020 13:17:29 +0800
Subject: [PATCH] head(1): Support '-q' and '-v' flags and improve man page

* Support the '-q' flag to never print headers of each filename, and the
  '-v' flag to always print the headers, which are the GNU extensions to
  this tool.
* Improve the man page to include the 'COMPATIBILITY' and 'STANDARDS'
  sections.

Obtained-from: NetBSD
---
 usr.bin/head/head.1 | 26 +++++++++++++++++++++-----
 usr.bin/head/head.c | 17 ++++++++++++++---
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/usr.bin/head/head.1 b/usr.bin/head/head.1
index 5eca08cef3..b82205d4cc 100644
--- a/usr.bin/head/head.1
+++ b/usr.bin/head/head.1
@@ -27,16 +27,16 @@
 .\"
 .\"	@(#)head.1	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD: src/usr.bin/head/head.1,v 1.4.2.6 2002/07/15 06:33:12 keramida Exp $
-.\" $DragonFly: src/usr.bin/head/head.1,v 1.3 2007/07/30 22:11:33 swildner Exp $
 .\"
-.Dd June 6, 1993
+.Dd June 19, 2020
 .Dt HEAD 1
 .Os
 .Sh NAME
 .Nm head
-.Nd display first lines of a file
+.Nd display the first part of files
 .Sh SYNOPSIS
 .Nm
+.Op Fl q | Fl v
 .Op Fl n Ar count | Fl c Ar bytes
 .Op Ar
 .Sh DESCRIPTION
@@ -50,16 +50,32 @@ If
 .Ar count
 is omitted it defaults to 10.
 .Pp
-If more than a single file is specified, each file is preceded by a
-header consisting of the string
+If more than a single file is specified, or the
+.Fl v
+flag is used, each file is preceded by a header consisting of the string
 .Dq ==> XXX <==
 where
 .Dq XXX
 is the name of the file.
+The
+.Fl q
+flag disables the printing of the header in both cases.
 .Sh EXIT STATUS
 .Ex -std
+.Sh COMPATIBILITY
+The historic command line syntax of
+.Nm
+is supported by this implementation.
+.Pp
+This command is mostly compatible with GNU extensions to
+.Nm .
 .Sh SEE ALSO
 .Xr tail 1
+.Sh STANDARDS
+The
+.Nm
+utility conforms to
+.St -p1003.2-92 .
 .Sh HISTORY
 The
 .Nm
diff --git a/usr.bin/head/head.c b/usr.bin/head/head.c
index 9f9b3e0b11..1046448f7e 100644
--- a/usr.bin/head/head.c
+++ b/usr.bin/head/head.c
@@ -55,11 +55,12 @@ main(int argc, char **argv)
 	int ch;
 	FILE *fp;
 	bool first;
+	bool qflag = false, vflag = false;
 	int linecnt = -1, bytecnt = -1, eval = 0;
 	char *ep;
 
 	obsolete(argv);
-	while ((ch = getopt(argc, argv, "n:c:")) != -1)
+	while ((ch = getopt(argc, argv, "c:n:qv")) != -1) {
 		switch(ch) {
 		case 'c':
 			bytecnt = strtol(optarg, &ep, 10);
@@ -71,9 +72,18 @@ main(int argc, char **argv)
 			if (*ep != 0 || linecnt <= 0)
 				errx(1, "illegal line count -- %s", optarg);
 			break;
+		case 'q':
+			qflag = true;
+			vflag = false;
+			break;
+		case 'v':
+			vflag = true;
+			qflag = false;
+			break;
 		default:
 			usage();
 		}
+	}
 	argc -= optind;
 	argv += optind;
 
@@ -89,7 +99,7 @@ main(int argc, char **argv)
 				eval = 1;
 				continue;
 			}
-			if (argc > 1) {
+			if (vflag || (!qflag && argc > 1)) {
 				printf("%s==> %s <==\n",
 				    first ? "" : "\n", *argv);
 				first = false;
@@ -163,6 +173,7 @@ obsolete(char **argv)
 static void __dead2
 usage(void)
 {
-	fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");
+	fprintf(stderr,
+		"usage: head [-q | -v] [-n lines | -c bytes] [file ...]\n");
 	exit(1);
 }
-- 
2.41.0