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head.c revision 1.7 
      1 /*	$NetBSD: head.c,v 1.7 1997/10/18 13:15:40 mrg Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1980, 1987, 1992, 1993
      5  *	The Regents of the University of California.  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 #include <sys/cdefs.h>
     37 #ifndef lint
     38 __COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
     39 	The Regents of the University of California.  All rights reserved.\n");
     40 #endif /* not lint */
     41 
     42 #ifndef lint
     43 #if 0
     44 static char sccsid[] = "@(#)head.c	8.2 (Berkeley) 5/4/95";
     45 #else
     46 __RCSID("$NetBSD: head.c,v 1.7 1997/10/18 13:15:40 mrg Exp $");
     47 #endif
     48 #endif /* not lint */
     49 
     50 #include <sys/types.h>
     51 
     52 #include <ctype.h>
     53 #include <errno.h>
     54 #include <stdio.h>
     55 #include <stdlib.h>
     56 #include <string.h>
     57 #include <unistd.h>
     58 
     59 /*
     60  * head - give the first few lines of a stream or of each of a set of files
     61  *
     62  * Bill Joy UCB August 24, 1977
     63  */
     64 
     65 void err __P((int, const char *, ...));
     66 void head __P((FILE *, int));
     67 void obsolete __P((char *[]));
     68 void usage __P((void));
     69 int main __P((int, char *[]));
     70 
     71 int eval;
     72 
     73 int
     74 main(argc, argv)
     75 	int argc;
     76 	char *argv[];
     77 {
     78 	register int ch;
     79 	FILE *fp;
     80 	int first, linecnt;
     81 	char *ep;
     82 
     83 	obsolete(argv);
     84 	linecnt = 10;
     85 	while ((ch = getopt(argc, argv, "n:")) != EOF)
     86 		switch(ch) {
     87 		case 'n':
     88 			linecnt = strtol(optarg, &ep, 10);
     89 			if (*ep || linecnt <= 0)
     90 				err(1, "illegal line count -- %s", optarg);
     91 			break;
     92 
     93 		case '?':
     94 		default:
     95 			usage();
     96 		}
     97 	argc -= optind;
     98 	argv += optind;
     99 
    100 	if (*argv)
    101 		for (first = 1; *argv; ++argv) {
    102 			if ((fp = fopen(*argv, "r")) == NULL) {
    103 				err(0, "%s: %s", *argv, strerror(errno));
    104 				continue;
    105 			}
    106 			if (argc > 1) {
    107 				(void)printf("%s==> %s <==\n",
    108 				    first ? "" : "\n", *argv);
    109 				first = 0;
    110 			}
    111 			head(fp, linecnt);
    112 			(void)fclose(fp);
    113 		}
    114 	else
    115 		head(stdin, linecnt);
    116 	exit(eval);
    117 }
    118 
    119 void
    120 head(fp, cnt)
    121 	FILE *fp;
    122 	register int cnt;
    123 {
    124 	register int ch;
    125 
    126 	while (cnt--)
    127 		while ((ch = getc(fp)) != EOF) {
    128 			if (putchar(ch) == EOF)
    129 				err(1, "stdout: %s", strerror(errno));
    130 			if (ch == '\n')
    131 				break;
    132 		}
    133 }
    134 
    135 void
    136 obsolete(argv)
    137 	char *argv[];
    138 {
    139 	char *ap;
    140 
    141 	while ((ap = *++argv)) {
    142 		/* Return if "--" or not "-[0-9]*". */
    143 		if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
    144 			return;
    145 		if ((ap = malloc(strlen(*argv) + 2)) == NULL)
    146 			err(1, "%s", strerror(errno));
    147 		ap[0] = '-';
    148 		ap[1] = 'n';
    149 		(void)strcpy(ap + 2, *argv + 1);
    150 		*argv = ap;
    151 	}
    152 }
    153 
    154 void
    155 usage()
    156 {
    157 	(void)fputs("usage: head [-n lines] [file ...]\n", stderr);
    158 	exit(1);
    159 }
    160