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[] = "@(#)head.c 5.5 (Berkeley) 6/1/90"; 42 #endif /* not lint */ 43 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <ctype.h> 47 48 static void usage (); 49 50 /* 51 * head - give the first few lines of a stream or of each of a set of files 52 * 53 * Bill Joy UCB August 24, 1977 54 */ 55 56 main(argc, argv) 57 int argc; 58 char **argv; 59 { 60 register int ch, cnt; 61 int firsttime, linecnt = 10; 62 63 /* handle obsolete -number syntax */ 64 if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) { 65 if ((linecnt = atoi(argv[1] + 1)) < 0) { 66 usage (); 67 } 68 argc--; argv++; 69 } 70 71 while ((ch = getopt (argc, argv, "n:")) != EOF) 72 switch (ch) { 73 case 'n': 74 if ((linecnt = atoi(optarg)) < 0) 75 usage (); 76 break; 77 78 default: 79 usage(); 80 } 81 argc -= optind, argv += optind; 82 83 /* setlinebuf(stdout); */ 84 for (firsttime = 1; ; firsttime = 0) { 85 if (!*argv) { 86 if (!firsttime) 87 exit(0); 88 } 89 else { 90 if (!freopen(*argv, "r", stdin)) { 91 fprintf(stderr, "head: can't read %s.\n", *argv); 92 exit(1); 93 } 94 if (argc > 1) { 95 if (!firsttime) 96 putchar('\n'); 97 printf("==> %s <==\n", *argv); 98 } 99 ++argv; 100 } 101 for (cnt = linecnt; cnt; --cnt) 102 while ((ch = getchar()) != EOF) 103 if (putchar(ch) == '\n') 104 break; 105 } 106 /*NOTREACHED*/ 107 } 108 109 110 static void 111 usage () 112 { 113 fputs("usage: head [-n line_count] [file ...]\n", stderr); 114 exit(1); 115 } 116 117