2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Edward Sze-Tyan Wang.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#) Copyright (c) 1991, 1993 The Regents of the University of California. All rights reserved.
37 * @(#)tail.c 8.1 (Berkeley) 6/6/93
38 * $FreeBSD: src/usr.bin/tail/tail.c,v 1.6.2.2 2001/12/19 20:29:31 iedowse Exp $
39 * $DragonFly: src/usr.bin/tail/tail.c,v 1.3 2003/10/04 20:36:52 hmp Exp $
42 #include <sys/types.h>
52 int Fflag, fflag, rflag, rval;
55 static void obsolete(char **);
56 static void usage(void);
59 main(int argc, char **argv)
69 * Tail's options are weird. First, -n10 is the same as -n-10, not
70 * -n+10. Second, the number options are 1 based and not offsets,
71 * so -n+1 is the first line, and -c-1 is the last byte. Third, the
72 * number options for the -r option specify the number of things that
73 * get displayed, not the starting point in the file. The one major
74 * incompatibility in this version as compared to historical versions
75 * is that the 'r' option couldn't be modified by the -lbc options,
76 * i.e. it was always done in lines. This version treats -rc as a
77 * number of characters in reverse order. Finally, the default for
78 * -r is the entire file, not 10 lines.
80 #define ARG(units, forward, backward) { \
83 off = strtoll(optarg, &p, 10) * (units); \
85 errx(1, "illegal offset -- %s", optarg); \
103 while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1)
105 case 'F': /* -F is superset of (and implies) -f */
109 ARG(512, FBYTES, RBYTES);
112 ARG(1, FBYTES, RBYTES);
118 ARG(1, FLINES, RLINES);
130 if (fflag && argc > 1)
131 errx(1, "-f option only appropriate for a single file");
134 * If displaying in reverse, don't permit follow option, and convert
142 else if (style == FLINES)
147 * If style not specified, the default is the whole file for -r, and
148 * the last 10 lines if not -r.
150 if (style == NOTSET) {
161 for (first = 1; fname = *argv++;) {
162 if ((fp = fopen(fname, "r")) == NULL ||
163 fstat(fileno(fp), &sb)) {
168 (void)printf("%s==> %s <==\n",
169 first ? "" : "\n", fname);
171 (void)fflush(stdout);
175 reverse(fp, style, off, &sb);
177 forward(fp, style, off, &sb);
183 if (fstat(fileno(stdin), &sb)) {
189 * Determine if input is a pipe. 4.4BSD will set the SOCKET
190 * bit in the st_mode field for pipes. Fix this then.
192 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
195 fflag = 0; /* POSIX.2 requires this. */
199 reverse(stdin, style, off, &sb);
201 forward(stdin, style, off, &sb);
207 * Convert the obsolete argument form into something that getopt can handle.
208 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
209 * the option argument for a -b, -c or -n option gets converted.
212 obsolete(char **argv)
218 while (ap = *++argv) {
219 /* Return if "--" or not an option of any form. */
223 } else if (ap[1] == '-')
227 /* Old-style option. */
228 case '0': case '1': case '2': case '3': case '4':
229 case '5': case '6': case '7': case '8': case '9':
231 /* Malloc space for dash, new option and argument. */
233 if ((start = p = malloc(len + 3)) == NULL)
238 * Go to the end of the option argument. Save off any
239 * trailing options (-3lf) and translate any trailing
240 * output style characters.
243 if (*t == 'F' || *t == 'f' || *t == 'r') {
259 case '0': case '1': case '2': case '3': case '4':
260 case '5': case '6': case '7': case '8': case '9':
264 errx(1, "illegal option -- %s", *argv);
272 * Options w/ arguments, skip the argument and continue
273 * with the next option.
281 /* Options w/o arguments, continue with the next option. */
287 /* Illegal option, return and let getopt handle it. */
297 (void)fprintf(stderr,
298 "usage: tail [-F | -f | -r] [-b # | -c # | -n #] [file ...]\n");