1 /* $NetBSD: head.c,v 1.6 1997/01/09 20:19:50 tls Exp $ */ 2 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";*/ 44 static char rcsid[] = "$NetBSD: head.c,v 1.6 1997/01/09 20:19:50 tls Exp $"; 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 76 while ((ch = getopt (argc, argv, "n:")) != EOF) 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 } 121 122