2 * Copyright (c) 1980, 1987, 1992, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 static const char copyright[] =
36 "@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
37 The Regents of the University of California. All rights reserved.\n";
42 static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95";
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
48 #include <sys/types.h>
59 * head - give the first few lines of a stream or of each of a set of files
61 * Bill Joy UCB August 24, 1977
64 static void head(FILE *, int);
65 static void head_bytes(FILE *, off_t);
66 static void obsolete(char *[]);
67 static void usage(void);
70 main(int argc, char *argv[])
74 int first, linecnt = -1, eval = 0;
79 while ((ch = getopt(argc, argv, "n:c:")) != -1)
82 bytecnt = strtoimax(optarg, &ep, 10);
83 if (*ep || bytecnt <= 0)
84 errx(1, "illegal byte count -- %s", optarg);
87 linecnt = strtol(optarg, &ep, 10);
88 if (*ep || linecnt <= 0)
89 errx(1, "illegal line count -- %s", optarg);
98 if (linecnt != -1 && bytecnt != -1)
99 errx(1, "can't combine line and byte counts");
103 for (first = 1; *argv; ++argv) {
104 if ((fp = fopen(*argv, "r")) == NULL) {
110 (void)printf("%s==> %s <==\n",
111 first ? "" : "\n", *argv);
117 head_bytes(fp, bytecnt);
120 } else if (bytecnt == -1)
121 head(stdin, linecnt);
123 head_bytes(stdin, bytecnt);
129 head(FILE *fp, int cnt)
132 size_t error, readlen;
134 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) {
135 error = fwrite(cp, sizeof(char), readlen, stdout);
136 if (error != readlen)
143 head_bytes(FILE *fp, off_t cnt)
149 if ((uintmax_t)cnt < sizeof(buf))
152 readlen = sizeof(buf);
153 readlen = fread(buf, sizeof(char), readlen, fp);
156 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen)
163 obsolete(char *argv[])
167 while ((ap = *++argv)) {
168 /* Return if "--" or not "-[0-9]*". */
169 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
171 if ((ap = malloc(strlen(*argv) + 2)) == NULL)
175 (void)strcpy(ap + 2, *argv + 1);
184 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");