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Annotation of src/usr.bin/head/head.c, Revision 1.6

1.6     ! kevlo       1: /*     $OpenBSD: head.c,v 1.5 1999/07/23 13:56:18 aaron 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.
                     15:  * 3. All advertising materials mentioning features or use of this software
                     16:  *    must display the following acknowledgement:
                     17:  *     This product includes software developed by the University of
                     18:  *     California, Berkeley and its contributors.
                     19:  * 4. Neither the name of the University nor the names of its contributors
                     20:  *    may be used to endorse or promote products derived from this software
                     21:  *    without specific prior written permission.
                     22:  *
                     23:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     24:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     25:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     26:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     27:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     28:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     29:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     30:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     31:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     32:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     33:  * SUCH DAMAGE.
                     34:  */
                     35:
                     36: #ifndef lint
                     37: char copyright[] =
                     38: "@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\
                     39:  All rights reserved.\n";
                     40: #endif /* not lint */
                     41:
                     42: #ifndef lint
                     43: /*static char sccsid[] = "from: @(#)head.c     5.5 (Berkeley) 6/1/90";*/
1.6     ! kevlo      44: static char rcsid[] = "$OpenBSD: head.c,v 1.5 1999/07/23 13:56:18 aaron Exp $";
1.1       deraadt    45: #endif /* not lint */
                     46:
                     47: #include <stdio.h>
                     48: #include <stdlib.h>
                     49: #include <ctype.h>
1.4       aaron      50: #include <limits.h>
                     51: #include <errno.h>
1.1       deraadt    52: #include <unistd.h>
                     53:
1.6     ! kevlo      54: static void usage __P((void));
1.1       deraadt    55:
                     56: /*
                     57:  * head - give the first few lines of a stream or of each of a set of files
                     58:  *
                     59:  * Bill Joy UCB August 24, 1977
                     60:  */
                     61:
                     62: int
                     63: main(argc, argv)
                     64:        int     argc;
                     65:        char    **argv;
                     66: {
1.4       aaron      67:        register long cnt;
                     68:        int     ch, firsttime;
                     69:        long    linecnt = 10;
                     70:        char    *inval = NULL, *p = NULL;
                     71:        size_t  len;
1.1       deraadt    72:
                     73:        /* handle obsolete -number syntax */
                     74:        if (argc > 1 && argv[1][0] == '-' && isdigit(argv[1][1])) {
1.4       aaron      75:                linecnt = strtol((p = argv[1] + 1), &inval, 10);
1.1       deraadt    76:                argc--; argv++;
                     77:        }
                     78:
1.3       millert    79:        while ((ch = getopt (argc, argv, "n:")) != -1)
1.1       deraadt    80:                switch (ch) {
                     81:                case 'n':
1.4       aaron      82:                        linecnt = strtol((p = optarg), &inval, 10);
1.1       deraadt    83:                        break;
                     84:                default:
                     85:                        usage();
                     86:                }
                     87:        argc -= optind, argv += optind;
                     88:
1.4       aaron      89:        if (p) {
                     90:                if ((linecnt == LONG_MIN || linecnt == LONG_MAX) &&
                     91:                    errno == ERANGE)
1.5       aaron      92:                        err(1, "illegal line count -- %s", p);
1.4       aaron      93:                else if (linecnt <= 0 || *inval)
1.5       aaron      94:                        errx(1, "illegal line count -- %s", p);
1.4       aaron      95:        }
                     96:
1.1       deraadt    97:        /* setlinebuf(stdout); */
                     98:        for (firsttime = 1; ; firsttime = 0) {
                     99:                if (!*argv) {
                    100:                        if (!firsttime)
                    101:                                exit(0);
                    102:                }
                    103:                else {
                    104:                        if (!freopen(*argv, "r", stdin)) {
1.5       aaron     105:                                warn("%s", *argv++);
1.4       aaron     106:                                continue;
1.1       deraadt   107:                        }
                    108:                        if (argc > 1) {
                    109:                                if (!firsttime)
                    110:                                        putchar('\n');
                    111:                                printf("==> %s <==\n", *argv);
                    112:                        }
                    113:                        ++argv;
                    114:                }
1.4       aaron     115:                for (cnt = linecnt; cnt && !feof(stdin); --cnt)
1.1       deraadt   116:                        while ((ch = getchar()) != EOF)
                    117:                                if (putchar(ch) == '\n')
                    118:                                        break;
                    119:        }
                    120:        /*NOTREACHED*/
                    121: }
                    122:
                    123:
                    124: static void
                    125: usage ()
                    126: {
                    127:        fputs("usage: head [-n line_count] [file ...]\n", stderr);
                    128:        exit(1);
                    129: }
                    130: