Annotation of src/usr.bin/head/head.c, Revision 1.3
1.3 ! millert 1: /* $OpenBSD: head.c,v 1.2 1996/06/26 05:34:15 deraadt Exp $ */
1.2 deraadt 2:
1.1 deraadt 3: /*
4: * Copyright (c) 1980, 1987 Regents of the University of California.
5: * All rights reserved.
6: *
7: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: * 3. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by the University of
18: * California, Berkeley and its contributors.
19: * 4. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #ifndef lint
37: char copyright[] =
38: "@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\
39: All rights reserved.\n";
40: #endif /* not lint */
41:
42: #ifndef lint
43: /*static char sccsid[] = "from: @(#)head.c 5.5 (Berkeley) 6/1/90";*/
1.3 ! millert 44: static char rcsid[] = "$OpenBSD: head.c,v 1.2 1996/06/26 05:34:15 deraadt Exp $";
1.1 deraadt 45: #endif /* not lint */
46:
47: #include <stdio.h>
48: #include <stdlib.h>
49: #include <ctype.h>
50: #include <unistd.h>
51:
52: static void usage ();
53:
54: /*
55: * head - give the first few lines of a stream or of each of a set of files
56: *
57: * Bill Joy UCB August 24, 1977
58: */
59:
60: int
61: main(argc, argv)
62: int argc;
63: char **argv;
64: {
65: register int ch, cnt;
66: int firsttime, linecnt = 10;
67:
68: /* handle obsolete -number syntax */
69: if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) {
70: if ((linecnt = atoi(argv[1] + 1)) < 0) {
71: usage ();
72: }
73: argc--; argv++;
74: }
75:
1.3 ! millert 76: while ((ch = getopt (argc, argv, "n:")) != -1)
1.1 deraadt 77: switch (ch) {
78: case 'n':
79: if ((linecnt = atoi(optarg)) < 0)
80: usage ();
81: break;
82:
83: default:
84: usage();
85: }
86: argc -= optind, argv += optind;
87:
88: /* setlinebuf(stdout); */
89: for (firsttime = 1; ; firsttime = 0) {
90: if (!*argv) {
91: if (!firsttime)
92: exit(0);
93: }
94: else {
95: if (!freopen(*argv, "r", stdin)) {
96: fprintf(stderr, "head: can't read %s.\n", *argv);
97: exit(1);
98: }
99: if (argc > 1) {
100: if (!firsttime)
101: putchar('\n');
102: printf("==> %s <==\n", *argv);
103: }
104: ++argv;
105: }
106: for (cnt = linecnt; cnt; --cnt)
107: while ((ch = getchar()) != EOF)
108: if (putchar(ch) == '\n')
109: break;
110: }
111: /*NOTREACHED*/
112: }
113:
114:
115: static void
116: usage ()
117: {
118: fputs("usage: head [-n line_count] [file ...]\n", stderr);
119: exit(1);
120: }
121: