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. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#) Copyright (c) 1980, 1987, 1992, 1993 The Regents of the University of California. All rights reserved.
30 * @(#)head.c 8.2 (Berkeley) 5/4/95
31 * $FreeBSD: src/usr.bin/head/head.c,v 1.10.2.1 2002/02/16 12:29:04 dwmalone Exp $
32 * $DragonFly: src/usr.bin/head/head.c,v 1.6 2008/06/05 18:06:33 swildner Exp $
43 * head - give the first few lines of a stream or of each of a set of files
45 * Bill Joy UCB August 24, 1977
48 static void head(FILE *, size_t);
49 static void head_bytes(FILE *, size_t);
50 static void obsolete(char *[]);
51 static void usage(void);
54 main(int argc, char **argv)
58 int first, linecnt = -1, bytecnt = -1, eval = 0;
62 while ((ch = getopt(argc, argv, "n:c:")) != -1)
65 bytecnt = strtol(optarg, &ep, 10);
66 if (*ep != 0 || bytecnt <= 0)
67 errx(1, "illegal byte count -- %s", optarg);
70 linecnt = strtol(optarg, &ep, 10);
71 if (*ep != 0 || linecnt <= 0)
72 errx(1, "illegal line count -- %s", optarg);
80 if (linecnt != -1 && bytecnt != -1)
81 errx(1, "can't combine line and byte counts");
85 for (first = 1; *argv; ++argv) {
86 if ((fp = fopen(*argv, "r")) == NULL) {
92 printf("%s==> %s <==\n",
93 first ? "" : "\n", *argv);
99 head_bytes(fp, bytecnt);
102 } else if (bytecnt == -1)
103 head(stdin, linecnt);
105 head_bytes(stdin, bytecnt);
111 head(FILE *fp, size_t cnt)
114 size_t error, readlen;
116 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) {
117 error = fwrite(cp, sizeof(char), readlen, stdout);
118 if (error != readlen)
125 head_bytes(FILE *fp, size_t cnt)
131 if (cnt < sizeof(buf))
134 readlen = sizeof(buf);
135 readlen = fread(buf, sizeof(char), readlen, fp);
138 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen)
145 obsolete(char **argv)
149 while ((ap = *++argv)) {
150 /* Return if "--" or not "-[0-9]*". */
151 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
153 if ((ap = malloc(strlen(*argv) + 2)) == NULL)
154 err(1, "malloc failed");
157 strcpy(ap + 2, *argv + 1);
165 fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");