Annotation of src/usr.bin/head/head.c, Revision 1.1.1.1
1.1 deraadt 1: /*
2: * Copyright (c) 1980, 1987 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
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.
20: *
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
31: * SUCH DAMAGE.
32: */
33:
34: #ifndef lint
35: char copyright[] =
36: "@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\
37: All rights reserved.\n";
38: #endif /* not lint */
39:
40: #ifndef lint
41: /*static char sccsid[] = "from: @(#)head.c 5.5 (Berkeley) 6/1/90";*/
42: static char rcsid[] = "$Id: head.c,v 1.5 1993/10/13 18:34:17 jtc Exp $";
43: #endif /* not lint */
44:
45: #include <stdio.h>
46: #include <stdlib.h>
47: #include <ctype.h>
48: #include <unistd.h>
49:
50: static void usage ();
51:
52: /*
53: * head - give the first few lines of a stream or of each of a set of files
54: *
55: * Bill Joy UCB August 24, 1977
56: */
57:
58: int
59: main(argc, argv)
60: int argc;
61: char **argv;
62: {
63: register int ch, cnt;
64: int firsttime, linecnt = 10;
65:
66: /* handle obsolete -number syntax */
67: if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) {
68: if ((linecnt = atoi(argv[1] + 1)) < 0) {
69: usage ();
70: }
71: argc--; argv++;
72: }
73:
74: while ((ch = getopt (argc, argv, "n:")) != EOF)
75: switch (ch) {
76: case 'n':
77: if ((linecnt = atoi(optarg)) < 0)
78: usage ();
79: break;
80:
81: default:
82: usage();
83: }
84: argc -= optind, argv += optind;
85:
86: /* setlinebuf(stdout); */
87: for (firsttime = 1; ; firsttime = 0) {
88: if (!*argv) {
89: if (!firsttime)
90: exit(0);
91: }
92: else {
93: if (!freopen(*argv, "r", stdin)) {
94: fprintf(stderr, "head: can't read %s.\n", *argv);
95: exit(1);
96: }
97: if (argc > 1) {
98: if (!firsttime)
99: putchar('\n');
100: printf("==> %s <==\n", *argv);
101: }
102: ++argv;
103: }
104: for (cnt = linecnt; cnt; --cnt)
105: while ((ch = getchar()) != EOF)
106: if (putchar(ch) == '\n')
107: break;
108: }
109: /*NOTREACHED*/
110: }
111:
112:
113: static void
114: usage ()
115: {
116: fputs("usage: head [-n line_count] [file ...]\n", stderr);
117: exit(1);
118: }
119: