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15637ed4 RG |
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[] = "@(#)head.c 5.5 (Berkeley) 6/1/90"; | |
42 | #endif /* not lint */ | |
43 | ||
44 | #include <stdio.h> | |
78ed81a3 | 45 | #include <stdlib.h> |
15637ed4 | 46 | #include <ctype.h> |
78ed81a3 | 47 | |
48 | static void usage (); | |
49 | ||
15637ed4 RG |
50 | /* |
51 | * head - give the first few lines of a stream or of each of a set of files | |
52 | * | |
53 | * Bill Joy UCB August 24, 1977 | |
54 | */ | |
55 | ||
56 | main(argc, argv) | |
57 | int argc; | |
58 | char **argv; | |
59 | { | |
60 | register int ch, cnt; | |
61 | int firsttime, linecnt = 10; | |
62 | ||
78ed81a3 | 63 | /* handle obsolete -number syntax */ |
64 | if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) { | |
15637ed4 | 65 | if ((linecnt = atoi(argv[1] + 1)) < 0) { |
78ed81a3 | 66 | usage (); |
15637ed4 | 67 | } |
78ed81a3 | 68 | argc--; argv++; |
15637ed4 | 69 | } |
78ed81a3 | 70 | |
71 | while ((ch = getopt (argc, argv, "n:")) != EOF) | |
72 | switch (ch) { | |
73 | case 'n': | |
74 | if ((linecnt = atoi(optarg)) < 0) | |
75 | usage (); | |
76 | break; | |
77 | ||
78 | default: | |
79 | usage(); | |
80 | } | |
81 | argc -= optind, argv += optind; | |
82 | ||
15637ed4 | 83 | /* setlinebuf(stdout); */ |
78ed81a3 | 84 | for (firsttime = 1; ; firsttime = 0) { |
15637ed4 RG |
85 | if (!*argv) { |
86 | if (!firsttime) | |
87 | exit(0); | |
88 | } | |
89 | else { | |
90 | if (!freopen(*argv, "r", stdin)) { | |
91 | fprintf(stderr, "head: can't read %s.\n", *argv); | |
92 | exit(1); | |
93 | } | |
94 | if (argc > 1) { | |
95 | if (!firsttime) | |
96 | putchar('\n'); | |
97 | printf("==> %s <==\n", *argv); | |
98 | } | |
99 | ++argv; | |
100 | } | |
101 | for (cnt = linecnt; cnt; --cnt) | |
102 | while ((ch = getchar()) != EOF) | |
103 | if (putchar(ch) == '\n') | |
104 | break; | |
105 | } | |
106 | /*NOTREACHED*/ | |
107 | } | |
78ed81a3 | 108 | |
109 | ||
110 | static void | |
111 | usage () | |
112 | { | |
113 | fputs("usage: head [-n line_count] [file ...]\n", stderr); | |
114 | exit(1); | |
115 | } | |
116 |