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/*
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 * Copyright (c) 1980, 1987, 1992, 1993
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 *        The Regents of the University of California.  All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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#include <sys/types.h>
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#include <ctype.h>
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#include <err.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/*
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 * head - give the first few lines of a stream or of each of a set of files
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 *
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 * Bill Joy UCB August 24, 1977
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 */
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#ifdef CMDBOX
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#define main(argc, argv)        head_main(argc, argv)
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#endif
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void head(FILE *, int);
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static void usage(void);
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int eval;
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int
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main(int argc, char *argv[])
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{
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        int ch;
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        FILE *fp;
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        int first, linecnt;
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        char *ep;
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        linecnt = 10;
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        while ((ch = getopt(argc, argv, "n:")) != EOF)
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                switch(ch) {
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                case 'n':
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                        linecnt = strtol(optarg, &ep, 10);
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                        if (*ep || linecnt <= 0)
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                                err(1, "illegal line count -- %s", optarg);
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                        break;
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                case '?':
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                default:
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                        usage();
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                }
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        argc -= optind;
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        argv += optind;
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        if (*argv)
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                for (first = 1; *argv; ++argv) {
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                        if ((fp = fopen(*argv, "r")) == NULL) {
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                                err(0, "%s: %s", *argv, strerror(errno));
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                                continue;
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                        }
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                        if (argc > 1) {
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                                (void)printf("%s==> %s <==\n",
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                                    first ? "" : "\n", *argv);
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                                first = 0;
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                        }
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                        head(fp, linecnt);
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                        (void)fclose(fp);
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                }
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        else
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                head(stdin, linecnt);
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        exit(eval);
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}
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void
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head(FILE *fp, int cnt)
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{
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        int ch;
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        while (cnt--)
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                while ((ch = getc(fp)) != EOF) {
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                        if (putchar(ch) == EOF)
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                                err(1, "stdout: %s", strerror(errno));
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                        if (ch == '\n')
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                                break;
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                }
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}
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static void
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usage()
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{
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        (void)fprintf(stderr, "usage: head [-n lines] [file ...]\n");
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        exit(1);
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}