2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * Edward Sze-Tyan Wang.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
40 static const char copyright[] =
41 "@(#) Copyright (c) 1991, 1993\n\
42 The Regents of the University of California. All rights reserved.\n";
46 static const char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93";
49 #include <sys/types.h>
62 int Fflag, fflag, qflag, rflag, rval, no_files;
64 static file_info_t *files;
66 static void obsolete(char **);
67 static void usage(void);
69 static const struct option long_opts[] =
71 {"blocks", required_argument, NULL, 'b'},
72 {"bytes", required_argument, NULL, 'c'},
73 {"lines", required_argument, NULL, 'n'},
74 {NULL, no_argument, NULL, 0}
78 main(int argc, char *argv[])
90 * Tail's options are weird. First, -n10 is the same as -n-10, not
91 * -n+10. Second, the number options are 1 based and not offsets,
92 * so -n+1 is the first line, and -c-1 is the last byte. Third, the
93 * number options for the -r option specify the number of things that
94 * get displayed, not the starting point in the file. The one major
95 * incompatibility in this version as compared to historical versions
96 * is that the 'r' option couldn't be modified by the -lbc options,
97 * i.e. it was always done in lines. This version treats -rc as a
98 * number of characters in reverse order. Finally, the default for
99 * -r is the entire file, not 10 lines.
101 #define ARG(units, forward, backward) { \
104 off = strtoll(optarg, &p, 10) * (units); \
106 errx(1, "illegal offset -- %s", optarg); \
107 switch(optarg[0]) { \
117 style = (backward); \
125 while ((ch = getopt_long(argc, argv, "+Fb:c:fn:qr", long_opts, NULL)) !=
128 case 'F': /* -F is superset of (and implies) -f */
132 ARG(512, FBYTES, RBYTES);
135 ARG(1, FBYTES, RBYTES);
141 ARG(1, FLINES, RLINES);
156 no_files = argc ? argc : 1;
159 * If displaying in reverse, don't permit follow option, and convert
167 else if (style == FLINES)
172 * If style not specified, the default is the whole file for -r, and
173 * the last 10 lines if not -r.
175 if (style == NOTSET) {
185 if (*argv && fflag) {
186 files = (struct file_info *) malloc(no_files *
187 sizeof(struct file_info));
189 err(1, "Couldn't malloc space for file descriptors.");
191 for (file = files; (fn = *argv++); file++) {
192 file->file_name = strdup(fn);
193 if (! file->file_name)
194 errx(1, "Couldn't malloc space for file name.");
195 if ((file->fp = fopen(file->file_name, "r")) == NULL ||
196 fstat(fileno(file->fp), &file->st)) {
197 if (file->fp != NULL) {
201 if (!Fflag || errno != ENOENT)
202 ierr(file->file_name);
205 follow(files, style, off);
206 for (i = 0, file = files; i < no_files; i++, file++) {
207 free(file->file_name);
211 for (first = 1; (fn = *argv++);) {
212 if ((fp = fopen(fn, "r")) == NULL ||
213 fstat(fileno(fp), &sb)) {
217 if (argc > 1 && !qflag) {
223 reverse(fp, fn, style, off, &sb);
225 forward(fp, fn, style, off, &sb);
230 if (fstat(fileno(stdin), &sb)) {
236 * Determine if input is a pipe. 4.4BSD will set the SOCKET
237 * bit in the st_mode field for pipes. Fix this then.
239 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
242 fflag = 0; /* POSIX.2 requires this. */
246 reverse(stdin, fn, style, off, &sb);
248 forward(stdin, fn, style, off, &sb);
254 * Convert the obsolete argument form into something that getopt can handle.
255 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
256 * the option argument for a -b, -c or -n option gets converted.
259 obsolete(char *argv[])
265 while ((ap = *++argv)) {
266 /* Return if "--" or not an option of any form. */
270 } else if (ap[1] == '-')
274 /* Old-style option. */
275 case '0': case '1': case '2': case '3': case '4':
276 case '5': case '6': case '7': case '8': case '9':
278 /* Malloc space for dash, new option and argument. */
280 if ((start = p = malloc(len + 3)) == NULL)
285 * Go to the end of the option argument. Save off any
286 * trailing options (-3lf) and translate any trailing
287 * output style characters.
290 if (*t == 'F' || *t == 'f' || *t == 'r') {
306 case '0': case '1': case '2': case '3': case '4':
307 case '5': case '6': case '7': case '8': case '9':
311 errx(1, "illegal option -- %s", *argv);
319 * Options w/ arguments, skip the argument and continue
320 * with the next option.
328 /* Options w/o arguments, continue with the next option. */
334 /* Illegal option, return and let getopt handle it. */
344 (void)fprintf(stderr,
345 "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"