freebsd-dev/usr.bin/head/head.c

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/*
* Copyright (c) 1980, 1987, 1992, 1993
* The 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
static char copyright[] =
"@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)head.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
/*
* head - give the first few lines of a stream or of each of a set of files
*
* Bill Joy UCB August 24, 1977
*/
void err __P((int, const char *, ...));
void head __P((FILE *, int));
void obsolete __P((char *[]));
void usage __P((void));
int eval;
int
main(argc, argv)
int argc;
char *argv[];
{
register int ch;
FILE *fp;
int first, linecnt;
char *ep;
obsolete(argv);
linecnt = 10;
while ((ch = getopt(argc, argv, "n:")) != EOF)
switch(ch) {
case 'n':
linecnt = strtol(optarg, &ep, 10);
if (*ep || linecnt <= 0)
err(1, "illegal line count -- %s", optarg);
break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
if (*argv)
for (first = 1; *argv; ++argv) {
if ((fp = fopen(*argv, "r")) == NULL) {
err(0, "%s: %s", *argv, strerror(errno));
continue;
}
if (argc > 1) {
(void)printf("%s==> %s <==\n",
first ? "" : "\n", *argv);
first = 0;
}
head(fp, linecnt);
(void)fclose(fp);
}
else
head(stdin, linecnt);
exit(eval);
}
void
head(fp, cnt)
FILE *fp;
register int cnt;
{
register int ch;
while (cnt && (ch = getc(fp)) != EOF) {
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if (putchar(ch) == EOF)
err(1, "stdout: %s", strerror(errno));
if (ch == '\n')
cnt--;
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}
}
void
obsolete(argv)
char *argv[];
{
char *ap;
while (ap = *++argv) {
/* Return if "--" or not "-[0-9]*". */
if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
return;
if ((ap = malloc(strlen(*argv) + 2)) == NULL)
err(1, "%s", strerror(errno));
ap[0] = '-';
ap[1] = 'n';
(void)strcpy(ap + 2, *argv + 1);
*argv = ap;
}
}
void
usage()
{
(void)fprintf(stderr, "usage: head [-n lines] [file ...]\n");
exit(1);
}
#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
void
#if __STDC__
err(int fatal, const char *fmt, ...)
#else
err(fatal, fmt, va_alist)
int fatal;
char *fmt;
va_dcl
#endif
{
va_list ap;
#if __STDC__
va_start(ap, fmt);
#else
va_start(ap);
#endif
(void)fprintf(stderr, "head: ");
(void)vfprintf(stderr, fmt, ap);
va_end(ap);
(void)fprintf(stderr, "\n");
if (fatal)
exit(1);
eval = 1;
}