1 /* $OpenBSD: head.c,v 1.11 2003/06/10 22:20:47 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. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #ifndef lint 33 char copyright[] = 34 "@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\ 35 All rights reserved.\n"; 36 #endif /* not lint */ 37 38 #ifndef lint 39 /*static char sccsid[] = "from: @(#)head.c 5.5 (Berkeley) 6/1/90";*/ 40 static char rcsid[] = "$OpenBSD: head.c,v 1.11 2003/06/10 22:20:47 deraadt Exp $"; 41 #endif /* not lint */ 42 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <ctype.h> 46 #include <limits.h> 47 #include <err.h> 48 #include <errno.h> 49 #include <unistd.h> 50 51 static void usage(void); 52 53 /* 54 * head - give the first few lines of a stream or of each of a set of files 55 * 56 * Bill Joy UCB August 24, 1977 57 */ 58 59 int 60 main(int argc, char *argv[]) 61 { 62 long cnt; 63 int ch, firsttime; 64 long linecnt = 10; 65 char *inval = NULL, *p = NULL; 66 67 /* handle obsolete -number syntax */ 68 if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) { 69 linecnt = strtol((p = argv[1] + 1), &inval, 10); 70 argc--; argv++; 71 } 72 73 while ((ch = getopt (argc, argv, "n:")) != -1) 74 switch (ch) { 75 case 'n': 76 linecnt = strtol((p = optarg), &inval, 10); 77 break; 78 default: 79 usage(); 80 } 81 argc -= optind, argv += optind; 82 83 if (p) { 84 if ((linecnt == LONG_MIN || linecnt == LONG_MAX) && 85 errno == ERANGE) 86 err(1, "illegal line count -- %s", p); 87 else if (linecnt <= 0 || *inval) 88 errx(1, "illegal line count -- %s", p); 89 } 90 91 /* setlinebuf(stdout); */ 92 for (firsttime = 1; ; firsttime = 0) { 93 if (!*argv) { 94 if (!firsttime) 95 exit(0); 96 } 97 else { 98 if (!freopen(*argv, "r", stdin)) { 99 warn("%s", *argv++); 100 continue; 101 } 102 if (argc > 1) { 103 if (!firsttime) 104 putchar('\n'); 105 printf("==> %s <==\n", *argv); 106 } 107 ++argv; 108 } 109 for (cnt = linecnt; cnt && !feof(stdin); --cnt) 110 while ((ch = getchar()) != EOF) 111 if (putchar(ch) == '\n') 112 break; 113 } 114 /*NOTREACHED*/ 115 } 116 117 118 static void 119 usage(void) 120 { 121 fputs("usage: head [-n line_count] [file ...]\n", stderr); 122 exit(1); 123 } 124 125