head.c revision 85859
155714Skris/* 255714Skris * Copyright (c) 1980, 1987, 1992, 1993 355714Skris * The Regents of the University of California. All rights reserved. 455714Skris * 555714Skris * Redistribution and use in source and binary forms, with or without 655714Skris * modification, are permitted provided that the following conditions 755714Skris * are met: 855714Skris * 1. Redistributions of source code must retain the above copyright 955714Skris * notice, this list of conditions and the following disclaimer. 1055714Skris * 2. Redistributions in binary form must reproduce the above copyright 1155714Skris * notice, this list of conditions and the following disclaimer in the 1255714Skris * documentation and/or other materials provided with the distribution. 1355714Skris * 3. All advertising materials mentioning features or use of this software 1455714Skris * must display the following acknowledgement: 1555714Skris * This product includes software developed by the University of 1655714Skris * California, Berkeley and its contributors. 1755714Skris * 4. Neither the name of the University nor the names of its contributors 1855714Skris * may be used to endorse or promote products derived from this software 1955714Skris * without specific prior written permission. 2055714Skris * 2155714Skris * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2255714Skris * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2355714Skris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2455714Skris * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 2555714Skris * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2655714Skris * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2755714Skris * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2855714Skris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2955714Skris * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 3055714Skris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 3155714Skris * SUCH DAMAGE. 3255714Skris */ 3355714Skris 3455714Skris#ifndef lint 3555714Skrisstatic const char copyright[] = 3655714Skris"@(#) Copyright (c) 1980, 1987, 1992, 1993\n\ 3755714Skris The Regents of the University of California. All rights reserved.\n"; 3855714Skris#endif /* not lint */ 3955714Skris 4055714Skris#ifndef lint 4155714Skris#if 0 4255714Skrisstatic char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95"; 4355714Skris#endif 4455714Skrisstatic const char rcsid[] = 4555714Skris "$FreeBSD: head/usr.bin/head/head.c 85859 2001-11-02 09:21:11Z alfred $"; 4655714Skris#endif /* not lint */ 4755714Skris 4855714Skris#include <sys/types.h> 4955714Skris 5055714Skris#include <ctype.h> 5155714Skris#include <err.h> 5255714Skris#include <stdio.h> 5355714Skris#include <stdlib.h> 5455714Skris#include <string.h> 55#include <unistd.h> 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 63void head __P((FILE *, int)); 64void head_bytes __P((FILE *, int)); 65void obsolete __P((char *[])); 66void usage __P((void)); 67 68int 69main(argc, argv) 70 int argc; 71 char *argv[]; 72{ 73 register int ch; 74 FILE *fp; 75 int first, linecnt = -1, bytecnt = -1, eval = 0; 76 char *ep; 77 78 obsolete(argv); 79 while ((ch = getopt(argc, argv, "n:c:")) != -1) 80 switch(ch) { 81 case 'c': 82 bytecnt = strtol(optarg, &ep, 10); 83 if (*ep || bytecnt <= 0) 84 errx(1, "illegal byte count -- %s", optarg); 85 break; 86 case 'n': 87 linecnt = strtol(optarg, &ep, 10); 88 if (*ep || linecnt <= 0) 89 errx(1, "illegal line count -- %s", optarg); 90 break; 91 case '?': 92 default: 93 usage(); 94 } 95 argc -= optind; 96 argv += optind; 97 98 if (linecnt != -1 && bytecnt != -1) 99 errx(1, "can't combine line and byte counts"); 100 if (linecnt == -1 ) 101 linecnt = 10; 102 if (*argv) { 103 for (first = 1; *argv; ++argv) { 104 if ((fp = fopen(*argv, "r")) == NULL) { 105 warn("%s", *argv); 106 eval = 1; 107 continue; 108 } 109 if (argc > 1) { 110 (void)printf("%s==> %s <==\n", 111 first ? "" : "\n", *argv); 112 first = 0; 113 } 114 if (bytecnt == -1) 115 head(fp, linecnt); 116 else 117 head_bytes(fp, bytecnt); 118 (void)fclose(fp); 119 } 120 } else if (bytecnt == -1) 121 head(stdin, linecnt); 122 else 123 head_bytes(stdin, bytecnt); 124 125 exit(eval); 126} 127 128void 129head(fp, cnt) 130 FILE *fp; 131 register int cnt; 132{ 133 register int ch; 134 135 while (cnt && (ch = getc(fp)) != EOF) { 136 if (putchar(ch) == EOF) 137 err(1, "stdout"); 138 if (ch == '\n') 139 cnt--; 140 } 141} 142 143void 144head_bytes(fp, cnt) 145 FILE *fp; 146 register int cnt; 147{ 148 char buf[4096]; 149 register int readlen; 150 151 while (cnt) { 152 if (cnt < sizeof(buf)) 153 readlen = cnt; 154 else 155 readlen = sizeof(buf); 156 readlen = fread(buf, sizeof(char), readlen, fp); 157 if (readlen == 0) 158 break; 159 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 160 err(1, "stdout"); 161 cnt -= readlen; 162 } 163} 164 165void 166obsolete(argv) 167 char *argv[]; 168{ 169 char *ap; 170 171 while ((ap = *++argv)) { 172 /* Return if "--" or not "-[0-9]*". */ 173 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 174 return; 175 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 176 err(1, NULL); 177 ap[0] = '-'; 178 ap[1] = 'n'; 179 (void)strcpy(ap + 2, *argv + 1); 180 *argv = ap; 181 } 182} 183 184void 185usage() 186{ 187 188 (void)fprintf(stderr, "usage: head [-n lines] [-c bytes] [file ...]\n"); 189 exit(1); 190} 191