1 /*
2 * Copyright (c) 1980, 1987, 1992, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 */
7
8 #ifndef lint
9 static char copyright[] =
10 "@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
11 The Regents of the University of California. All rights reserved.\n";
12 #endif /* not lint */
13
14 #ifndef lint
15 static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 05/04/95";
16 #endif /* not lint */
17
18 #include <sys/types.h>
19
20 #include <ctype.h>
21 #include <errno.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <unistd.h>
26
27 /*
28 * head - give the first few lines of a stream or of each of a set of files
29 *
30 * Bill Joy UCB August 24, 1977
31 */
32
33 void err __P((int, const char *, ...));
34 void head __P((FILE *, int));
35 void obsolete __P((char *[]));
36 void usage __P((void));
37
38 int eval;
39
40 int
main(argc,argv)41 main(argc, argv)
42 int argc;
43 char *argv[];
44 {
45 register int ch;
46 FILE *fp;
47 int first, linecnt;
48 char *ep;
49
50 obsolete(argv);
51 linecnt = 10;
52 while ((ch = getopt(argc, argv, "n:")) != EOF)
53 switch(ch) {
54 case 'n':
55 linecnt = strtol(optarg, &ep, 10);
56 if (*ep || linecnt <= 0)
57 err(1, "illegal line count -- %s", optarg);
58 break;
59 case '?':
60 default:
61 usage();
62 }
63 argc -= optind;
64 argv += optind;
65
66 if (*argv)
67 for (first = 1; *argv; ++argv) {
68 if ((fp = fopen(*argv, "r")) == NULL) {
69 err(0, "%s: %s", *argv, strerror(errno));
70 continue;
71 }
72 if (argc > 1) {
73 (void)printf("%s==> %s <==\n",
74 first ? "" : "\n", *argv);
75 first = 0;
76 }
77 head(fp, linecnt);
78 (void)fclose(fp);
79 }
80 else
81 head(stdin, linecnt);
82 exit(eval);
83 }
84
85 void
head(fp,cnt)86 head(fp, cnt)
87 FILE *fp;
88 register int cnt;
89 {
90 register int ch;
91
92 while (cnt--)
93 while ((ch = getc(fp)) != EOF) {
94 if (putchar(ch) == EOF)
95 err(1, "stdout: %s", strerror(errno));
96 if (ch == '\n')
97 break;
98 }
99 }
100
101 void
obsolete(argv)102 obsolete(argv)
103 char *argv[];
104 {
105 char *ap;
106
107 while (ap = *++argv) {
108 /* Return if "--" or not "-[0-9]*". */
109 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
110 return;
111 if ((ap = malloc(strlen(*argv) + 2)) == NULL)
112 err(1, "%s", strerror(errno));
113 ap[0] = '-';
114 ap[1] = 'n';
115 (void)strcpy(ap + 2, *argv + 1);
116 *argv = ap;
117 }
118 }
119
120 void
usage()121 usage()
122 {
123 (void)fprintf(stderr, "usage: head [-n lines] [file ...]\n");
124 exit(1);
125 }
126
127 #if __STDC__
128 #include <stdarg.h>
129 #else
130 #include <varargs.h>
131 #endif
132
133 void
134 #if __STDC__
err(int fatal,const char * fmt,...)135 err(int fatal, const char *fmt, ...)
136 #else
137 err(fatal, fmt, va_alist)
138 int fatal;
139 char *fmt;
140 va_dcl
141 #endif
142 {
143 va_list ap;
144 #if __STDC__
145 va_start(ap, fmt);
146 #else
147 va_start(ap);
148 #endif
149 (void)fprintf(stderr, "head: ");
150 (void)vfprintf(stderr, fmt, ap);
151 va_end(ap);
152 (void)fprintf(stderr, "\n");
153 if (fatal)
154 exit(1);
155 eval = 1;
156 }
157