Hi
reversing lines currently:
BSDs: tail -r
GNU: tac
Anyone writing portable code: sed '1!G;h;$!d'
(Yes that actually works)
Attached diff adds a hard link tac (need set lists adjusted though, and
I have a man page). it doesn't add any of the GNU tac options.
Cost: a hard link.
Index: Makefile
===================================================================
RCS file: /cvsroot/src/usr.bin/tail/Makefile,v
retrieving revision 1.3
diff -u -r1.3 Makefile
--- Makefile 23 Nov 1994 07:41:55 -0000 1.3
+++ Makefile 1 Oct 2017 14:42:34 -0000
@@ -1,7 +1,8 @@
# $NetBSD: Makefile,v 1.3 1994/11/23 07:41:55 jtc Exp $
# @(#)Makefile 8.1 (Berkeley) 6/6/93
-
PROG= tail
SRCS= forward.c misc.c read.c reverse.c tail.c
+LINKS= ${BINDIR}/tail ${BINDIR}/tac
+
.include <bsd.prog.mk>
Index: tail.c
===================================================================
RCS file: /cvsroot/src/usr.bin/tail/tail.c,v
retrieving revision 1.17
diff -u -r1.17 tail.c
--- tail.c 31 Jan 2013 23:09:06 -0000 1.17
+++ tail.c 1 Oct 2017 14:42:34 -0000
@@ -105,30 +105,35 @@
obsolete(argv);
style = NOTSET;
- while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1)
- switch(ch) {
- case 'F':
- fflag = 2;
- break;
- case 'b':
- ARG(512, FBYTES, RBYTES);
- break;
- case 'c':
- ARG(1, FBYTES, RBYTES);
- break;
- case 'f':
- fflag = 1;
- break;
- case 'n':
- ARG(1, FLINES, RLINES);
- break;
- case 'r':
- rflag = 1;
- break;
- case '?':
- default:
- usage();
- }
+ if (strcmp(getprogname(), "tail") == 0) {
+ while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1)
+ switch(ch) {
+ case 'F':
+ fflag = 2;
+ break;
+ case 'b':
+ ARG(512, FBYTES, RBYTES);
+ break;
+ case 'c':
+ ARG(1, FBYTES, RBYTES);
+ break;
+ case 'f':
+ fflag = 1;
+ break;
+ case 'n':
+ ARG(1, FLINES, RLINES);
+ break;
+ case 'r':
+ rflag = 1;
+ break;
+ case '?':
+ default:
+ usage();
+ }
+ } else { /* tac */
+ rflag = 1;
+ }
+
argc -= optind;
argv += optind;
