1 /* $OpenBSD: head.c,v 1.7 2001/07/04 06:31:25 deraadt 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[] = "$OpenBSD: head.c,v 1.7 2001/07/04 06:31:25 deraadt Exp $"; 45 #endif /* not lint */ 46 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <ctype.h> 50 #include <limits.h> 51 #include <err.h> 52 #include <errno.h> 53 #include <unistd.h> 54 55 static void usage __P((void)); 56 57 /* 58 * head - give the first few lines of a stream or of each of a set of files 59 * 60 * Bill Joy UCB August 24, 1977 61 */ 62 63 int 64 main(argc, argv) 65 int argc; 66 char **argv; 67 { 68 register long cnt; 69 int ch, firsttime; 70 long linecnt = 10; 71 char *inval = NULL, *p = NULL; 72 73 /* handle obsolete -number syntax */ 74 if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) { 75 linecnt = strtol((p = argv[1] + 1), &inval, 10); 76 argc--; argv++; 77 } 78 79 while ((ch = getopt (argc, argv, "n:")) != -1) 80 switch (ch) { 81 case 'n': 82 linecnt = strtol((p = optarg), &inval, 10); 83 break; 84 default: 85 usage(); 86 } 87 argc -= optind, argv += optind; 88 89 if (p) { 90 if ((linecnt == LONG_MIN || linecnt == LONG_MAX) && 91 errno == ERANGE) 92 err(1, "illegal line count -- %s", p); 93 else if (linecnt <= 0 || *inval) 94 errx(1, "illegal line count -- %s", p); 95 } 96 97 /* setlinebuf(stdout); */ 98 for (firsttime = 1; ; firsttime = 0) { 99 if (!*argv) { 100 if (!firsttime) 101 exit(0); 102 } 103 else { 104 if (!freopen(*argv, "r", stdin)) { 105 warn("%s", *argv++); 106 continue; 107 } 108 if (argc > 1) { 109 if (!firsttime) 110 putchar('\n'); 111 printf("==> %s <==\n", *argv); 112 } 113 ++argv; 114 } 115 for (cnt = linecnt; cnt && !feof(stdin); --cnt) 116 while ((ch = getchar()) != EOF) 117 if (putchar(ch) == '\n') 118 break; 119 } 120 /*NOTREACHED*/ 121 } 122 123 124 static void 125 usage () 126 { 127 fputs("usage: head [-n line_count] [file ...]\n", stderr); 128 exit(1); 129 } 130 131