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Annotation of src/usr.bin/head/head.c, Revision 1.15

1.15    ! deraadt     1: /*     $OpenBSD: head.c,v 1.14 2007/10/31 16:29:50 jmc Exp $   */
1.2       deraadt     2:
1.1       deraadt     3: /*
                      4:  * Copyright (c) 1980, 1987 Regents of the University of California.
                      5:  * 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.
1.10      millert    15:  * 3. Neither the name of the University nor the names of its contributors
1.1       deraadt    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 <stdio.h>
                     33: #include <stdlib.h>
                     34: #include <ctype.h>
1.4       aaron      35: #include <limits.h>
1.7       deraadt    36: #include <err.h>
1.4       aaron      37: #include <errno.h>
1.1       deraadt    38: #include <unistd.h>
                     39:
1.8       millert    40: static void usage(void);
1.1       deraadt    41:
                     42: /*
                     43:  * head - give the first few lines of a stream or of each of a set of files
                     44:  *
                     45:  * Bill Joy UCB August 24, 1977
                     46:  */
                     47:
                     48: int
1.11      deraadt    49: main(int argc, char *argv[])
1.1       deraadt    50: {
1.9       mpech      51:        long    cnt;
1.4       aaron      52:        int     ch, firsttime;
                     53:        long    linecnt = 10;
1.12      ray        54:        char    *p = NULL;
1.1       deraadt    55:
                     56:        /* handle obsolete -number syntax */
                     57:        if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) {
1.12      ray        58:                p = argv[1] + 1;
1.13      tedu       59:                argc--;
                     60:                argv++;
1.1       deraadt    61:        }
                     62:
1.13      tedu       63:        while ((ch = getopt(argc, argv, "n:")) != -1) {
1.1       deraadt    64:                switch (ch) {
                     65:                case 'n':
1.12      ray        66:                        p = optarg;
1.1       deraadt    67:                        break;
                     68:                default:
                     69:                        usage();
                     70:                }
1.13      tedu       71:        }
1.1       deraadt    72:        argc -= optind, argv += optind;
                     73:
1.4       aaron      74:        if (p) {
1.12      ray        75:                const char *errstr;
                     76:
                     77:                linecnt = strtonum(p, 1, LONG_MAX, &errstr);
                     78:                if (errstr)
                     79:                        errx(1, "line count %s: %s", errstr, p);
1.4       aaron      80:        }
                     81:
1.1       deraadt    82:        /* setlinebuf(stdout); */
                     83:        for (firsttime = 1; ; firsttime = 0) {
                     84:                if (!*argv) {
                     85:                        if (!firsttime)
                     86:                                exit(0);
1.13      tedu       87:                } else {
1.1       deraadt    88:                        if (!freopen(*argv, "r", stdin)) {
1.5       aaron      89:                                warn("%s", *argv++);
1.4       aaron      90:                                continue;
1.1       deraadt    91:                        }
                     92:                        if (argc > 1) {
                     93:                                if (!firsttime)
                     94:                                        putchar('\n');
                     95:                                printf("==> %s <==\n", *argv);
                     96:                        }
                     97:                        ++argv;
                     98:                }
1.4       aaron      99:                for (cnt = linecnt; cnt && !feof(stdin); --cnt)
1.1       deraadt   100:                        while ((ch = getchar()) != EOF)
                    101:                                if (putchar(ch) == '\n')
                    102:                                        break;
                    103:        }
                    104:        /*NOTREACHED*/
                    105: }
                    106:
                    107:
                    108: static void
1.11      deraadt   109: usage(void)
1.1       deraadt   110: {
1.14      jmc       111:        fputs("usage: head [-count | -n count] [file ...]\n", stderr);
1.1       deraadt   112:        exit(1);
                    113: }