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head.c revision 1.17 
      1 /*	$NetBSD: head.c,v 1.17 2004/01/05 23:23:34 jmmv 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. 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 #include <sys/cdefs.h>
     33 #ifndef lint
     34 __COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
     35 	The Regents of the University of California.  All rights reserved.\n");
     36 #endif /* not lint */
     37 
     38 #ifndef lint
     39 #if 0
     40 static char sccsid[] = "@(#)head.c	8.2 (Berkeley) 5/4/95";
     41 #else
     42 __RCSID("$NetBSD: head.c,v 1.17 2004/01/05 23:23:34 jmmv Exp $");
     43 #endif
     44 #endif /* not lint */
     45 
     46 #include <sys/types.h>
     47 
     48 #include <ctype.h>
     49 #include <err.h>
     50 #include <errno.h>
     51 #include <limits.h>
     52 #include <locale.h>
     53 #include <stdio.h>
     54 #include <stdlib.h>
     55 #include <string.h>
     56 #include <unistd.h>
     57 
     58 /*
     59  * head - give the first few lines of a stream or of each of a set of files
     60  *
     61  * Bill Joy UCB August 24, 1977
     62  */
     63 
     64 void head __P((FILE *, long));
     65 void obsolete __P((char *[]));
     66 void usage __P((void));
     67 int main __P((int, char *[]));
     68 
     69 int eval = 0;
     70 
     71 int
     72 main(argc, argv)
     73 	int argc;
     74 	char *argv[];
     75 {
     76 	int ch;
     77 	FILE *fp;
     78 	int first;
     79 	long linecnt;
     80 	char *ep;
     81 
     82 	(void)setlocale(LC_ALL, "");
     83 	obsolete(argv);
     84 	linecnt = 10;
     85 	while ((ch = getopt(argc, argv, "n:")) != -1)
     86 		switch(ch) {
     87 		case 'n':
     88 			errno = 0;
     89 			linecnt = strtol(optarg, &ep, 10);
     90 			if ((linecnt == LONG_MIN || linecnt == LONG_MAX) &&
     91 			    errno == ERANGE)
     92 				err(1, "illegal line count -- %s", optarg);
     93 			else if (*ep || linecnt <= 0)
     94 				errx(1, "illegal line count -- %s", optarg);
     95 			break;
     96 
     97 		case '?':
     98 		default:
     99 			usage();
    100 		}
    101 	argc -= optind;
    102 	argv += optind;
    103 
    104 	if (*argv)
    105 		for (first = 1; *argv; ++argv) {
    106 			if ((fp = fopen(*argv, "r")) == NULL) {
    107 				warn("%s", *argv);
    108 				eval = 1;
    109 				continue;
    110 			}
    111 			if (argc > 1) {
    112 				(void)printf("%s==> %s <==\n",
    113 				    first ? "" : "\n", *argv);
    114 				first = 0;
    115 			}
    116 			head(fp, linecnt);
    117 			(void)fclose(fp);
    118 		}
    119 	else
    120 		head(stdin, linecnt);
    121 	exit(eval);
    122 }
    123 
    124 void
    125 head(fp, cnt)
    126 	FILE *fp;
    127 	long cnt;
    128 {
    129 	int ch;
    130 
    131 	while (cnt--)
    132 		while ((ch = getc(fp)) != EOF) {
    133 			if (putchar(ch) == EOF)
    134 				err(1, "stdout");
    135 			if (ch == '\n')
    136 				break;
    137 		}
    138 }
    139 
    140 void
    141 obsolete(argv)
    142 	char *argv[];
    143 {
    144 	char *ap;
    145 
    146 	while ((ap = *++argv)) {
    147 		/* Return if "--" or not "-[0-9]*". */
    148 		if (ap[0] != '-' || ap[1] == '-' ||
    149 		    !isdigit((unsigned char)ap[1]))
    150 			return;
    151 		if ((ap = malloc(strlen(*argv) + 2)) == NULL)
    152 			err(1, NULL);
    153 		ap[0] = '-';
    154 		ap[1] = 'n';
    155 		(void)strcpy(ap + 2, *argv + 1);
    156 		*argv = ap;
    157 	}
    158 }
    159 
    160 void
    161 usage()
    162 {
    163 
    164 	(void)fprintf(stderr, "usage: %s [-n lines] [file ...]\n",
    165 	    getprogname());
    166 	exit(1);
    167 }
    168