Colony » Colony Scout

/*

 * 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. 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.

 */

#include <sys/types.h>

#include <ctype.h>

#include <err.h>

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

/*

 * head - give the first few lines of a stream or of each of a set of files

 *

 * Bill Joy UCB August 24, 1977

 */

#ifdef CMDBOX

#define main(argc, argv)        head_main(argc, argv)

#endif

void head(FILE *, int);

static void usage(void);

int eval;

int

main(int argc, char *argv[])

{

        int ch;

        FILE *fp;

        int first, linecnt;

        char *ep;

        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(FILE *fp, int cnt)

{

        int ch;

        while (cnt--)

                while ((ch = getc(fp)) != EOF) {

                        if (putchar(ch) == EOF)

                                err(1, "stdout: %s", strerror(errno));

                        if (ch == '\n')

                                break;

                }

}

static void

usage()

{

        (void)fprintf(stderr, "usage: head [-n lines] [file ...]\n");

        exit(1);

}