/* $OpenBSD: head.c,v 1.3 1997/01/15 23:42:33 millert Exp $ */ /* * Copyright (c) 1980, 1987 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef lint char copyright[] = "@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\ All rights reserved.\n"; #endif /* not lint */ #ifndef lint /*static char sccsid[] = "from: @(#)head.c 5.5 (Berkeley) 6/1/90";*/ static char rcsid[] = "$OpenBSD: head.c,v 1.3 1997/01/15 23:42:33 millert Exp $"; #endif /* not lint */ #include <stdio.h> #include <stdlib.h> #include <ctype.h> #include <unistd.h> static void usage (); /* * head - give the first few lines of a stream or of each of a set of files * * Bill Joy UCB August 24, 1977 */ int main(argc, argv) int argc; char **argv; { register int ch, cnt; int firsttime, linecnt = 10; /* handle obsolete -number syntax */ if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) { if ((linecnt = atoi(argv[1] + 1)) < 0) { usage (); } argc--; argv++; } while ((ch = getopt (argc, argv, "n:")) != -1) switch (ch) { case 'n': if ((linecnt = atoi(optarg)) < 0) usage (); break; default: usage(); } argc -= optind, argv += optind; /* setlinebuf(stdout); */ for (firsttime = 1; ; firsttime = 0) { if (!*argv) { if (!firsttime) exit(0); } else { if (!freopen(*argv, "r", stdin)) { fprintf(stderr, "head: can't read %s.\n", *argv); exit(1); } if (argc > 1) { if (!firsttime) putchar('\n'); printf("==> %s <==\n", *argv); } ++argv; } for (cnt = linecnt; cnt; --cnt) while ((ch = getchar()) != EOF) if (putchar(ch) == '\n') break; } /*NOTREACHED*/ } static void usage () { fputs("usage: head [-n line_count] [file ...]\n", stderr); exit(1); }