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 1.5 1993/10/13 18:34:17 jtc Exp $"; 43 #endif /* not lint */ 44 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <ctype.h> 48 #include <unistd.h> 49 50 static void usage (); 51 52 /* 53 * head - give the first few lines of a stream or of each of a set of files 54 * 55 * Bill Joy UCB August 24, 1977 56 */ 57 58 int 59 main(argc, argv) 60 int argc; 61 char **argv; 62 { 63 register int ch, cnt; 64 int firsttime, linecnt = 10; 65 66 /* handle obsolete -number syntax */ 67 if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) { 68 if ((linecnt = atoi(argv[1] + 1)) < 0) { 69 usage (); 70 } 71 argc--; argv++; 72 } 73 74 while ((ch = getopt (argc, argv, "n:")) != EOF) 75 switch (ch) { 76 case 'n': 77 if ((linecnt = atoi(optarg)) < 0) 78 usage (); 79 break; 80 81 default: 82 usage(); 83 } 84 argc -= optind, argv += optind; 85 86 /* setlinebuf(stdout); */ 87 for (firsttime = 1; ; firsttime = 0) { 88 if (!*argv) { 89 if (!firsttime) 90 exit(0); 91 } 92 else { 93 if (!freopen(*argv, "r", stdin)) { 94 fprintf(stderr, "head: can't read %s.\n", *argv); 95 exit(1); 96 } 97 if (argc > 1) { 98 if (!firsttime) 99 putchar('\n'); 100 printf("==> %s <==\n", *argv); 101 } 102 ++argv; 103 } 104 for (cnt = linecnt; cnt; --cnt) 105 while ((ch = getchar()) != EOF) 106 if (putchar(ch) == '\n') 107 break; 108 } 109 /*NOTREACHED*/ 110 } 111 112 113 static void 114 usage () 115 { 116 fputs("usage: head [-n line_count] [file ...]\n", stderr); 117 exit(1); 118 } 119 120