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 1.4 1993/08/27 22:30:27 jtc Exp $"; 43 #endif /* not lint */ 44 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <ctype.h> 48 49 static void usage (); 50 51 /* 52 * head - give the first few lines of a stream or of each of a set of files 53 * 54 * Bill Joy UCB August 24, 1977 55 */ 56 57 int 58 main(argc, argv) 59 int argc; 60 char **argv; 61 { 62 register int ch, cnt; 63 int firsttime, linecnt = 10; 64 65 /* handle obsolete -number syntax */ 66 if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) { 67 if ((linecnt = atoi(argv[1] + 1)) < 0) { 68 usage (); 69 } 70 argc--; argv++; 71 } 72 73 while ((ch = getopt (argc, argv, "n:")) != EOF) 74 switch (ch) { 75 case 'n': 76 if ((linecnt = atoi(optarg)) < 0) 77 usage (); 78 break; 79 80 default: 81 usage(); 82 } 83 argc -= optind, argv += optind; 84 85 /* setlinebuf(stdout); */ 86 for (firsttime = 1; ; firsttime = 0) { 87 if (!*argv) { 88 if (!firsttime) 89 exit(0); 90 } 91 else { 92 if (!freopen(*argv, "r", stdin)) { 93 fprintf(stderr, "head: can't read %s.\n", *argv); 94 exit(1); 95 } 96 if (argc > 1) { 97 if (!firsttime) 98 putchar('\n'); 99 printf("==> %s <==\n", *argv); 100 } 101 ++argv; 102 } 103 for (cnt = linecnt; cnt; --cnt) 104 while ((ch = getchar()) != EOF) 105 if (putchar(ch) == '\n') 106 break; 107 } 108 /*NOTREACHED*/ 109 } 110 111 112 static void 113 usage () 114 { 115 fputs("usage: head [-n line_count] [file ...]\n", stderr); 116 exit(1); 117 } 118 119