Annotation of prex/usr/bin/head/head.c, Revision 1.1.1.1
1.1 nbrk 1: /*
2: * Copyright (c) 1980, 1987, 1992, 1993
3: * The Regents of the University of California. 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. 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.
16: *
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
27: * SUCH DAMAGE.
28: */
29:
30: #include <sys/types.h>
31:
32: #include <ctype.h>
33: #include <err.h>
34: #include <errno.h>
35: #include <stdio.h>
36: #include <stdlib.h>
37: #include <string.h>
38: #include <unistd.h>
39:
40: /*
41: * head - give the first few lines of a stream or of each of a set of files
42: *
43: * Bill Joy UCB August 24, 1977
44: */
45:
46: #ifdef CMDBOX
47: #define main(argc, argv) head_main(argc, argv)
48: #endif
49:
50: void head(FILE *, int);
51: void obsolete(char *[]);
52: static void usage(void);
53:
54: int eval;
55:
56: int
57: main(int argc, char *argv[])
58: {
59: register int ch;
60: FILE *fp;
61: int first, linecnt;
62: char *ep;
63:
64: obsolete(argv);
65: linecnt = 10;
66: while ((ch = getopt(argc, argv, "n:")) != EOF)
67: switch(ch) {
68: case 'n':
69: linecnt = strtol(optarg, &ep, 10);
70: if (*ep || linecnt <= 0)
71: err(1, "illegal line count -- %s", optarg);
72: break;
73: case '?':
74: default:
75: usage();
76: }
77: argc -= optind;
78: argv += optind;
79:
80: if (*argv)
81: for (first = 1; *argv; ++argv) {
82: if ((fp = fopen(*argv, "r")) == NULL) {
83: err(0, "%s: %s", *argv, strerror(errno));
84: continue;
85: }
86: if (argc > 1) {
87: (void)printf("%s==> %s <==\n",
88: first ? "" : "\n", *argv);
89: first = 0;
90: }
91: head(fp, linecnt);
92: (void)fclose(fp);
93: }
94: else
95: head(stdin, linecnt);
96: exit(eval);
97: }
98:
99: void
100: head(fp, cnt)
101: FILE *fp;
102: register int cnt;
103: {
104: register int ch;
105:
106: while (cnt--)
107: while ((ch = getc(fp)) != EOF) {
108: if (putchar(ch) == EOF)
109: err(1, "stdout: %s", strerror(errno));
110: if (ch == '\n')
111: break;
112: }
113: }
114:
115: void
116: obsolete(argv)
117: char *argv[];
118: {
119: char *ap;
120:
121: while ((ap = *++argv)) {
122: /* Return if "--" or not "-[0-9]*". */
123: if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
124: return;
125: if ((ap = malloc(strlen(*argv) + 2)) == NULL)
126: err(1, "%s", strerror(errno));
127: ap[0] = '-';
128: ap[1] = 'n';
129: (void)strcpy(ap + 2, *argv + 1);
130: *argv = ap;
131: }
132: }
133:
134: static void
135: usage()
136: {
137: (void)fprintf(stderr, "usage: head [-n lines] [file ...]\n");
138: exit(1);
139: }
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