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Annotation of src/usr.bin/head/head.c, Revision 1.18

1.18    ! schwarze    1: /*     $OpenBSD: head.c,v 1.17 2014/10/07 19:38:57 tedu 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: {
1.18    ! schwarze   51:        FILE    *fp;
1.9       mpech      52:        long    cnt;
1.4       aaron      53:        int     ch, firsttime;
                     54:        long    linecnt = 10;
1.12      ray        55:        char    *p = NULL;
1.17      tedu       56:        int     status = 0;
1.1       deraadt    57:
                     58:        /* handle obsolete -number syntax */
1.16      deraadt    59:        if (argc > 1 && argv[1][0] == '-' &&
                     60:            isdigit((unsigned char)argv[1][1])) {
1.12      ray        61:                p = argv[1] + 1;
1.13      tedu       62:                argc--;
                     63:                argv++;
1.1       deraadt    64:        }
                     65:
1.13      tedu       66:        while ((ch = getopt(argc, argv, "n:")) != -1) {
1.1       deraadt    67:                switch (ch) {
                     68:                case 'n':
1.12      ray        69:                        p = optarg;
1.1       deraadt    70:                        break;
                     71:                default:
                     72:                        usage();
                     73:                }
1.13      tedu       74:        }
1.1       deraadt    75:        argc -= optind, argv += optind;
                     76:
1.4       aaron      77:        if (p) {
1.12      ray        78:                const char *errstr;
                     79:
                     80:                linecnt = strtonum(p, 1, LONG_MAX, &errstr);
                     81:                if (errstr)
                     82:                        errx(1, "line count %s: %s", errstr, p);
1.4       aaron      83:        }
                     84:
1.1       deraadt    85:        for (firsttime = 1; ; firsttime = 0) {
                     86:                if (!*argv) {
                     87:                        if (!firsttime)
1.17      tedu       88:                                exit(status);
1.18    ! schwarze   89:                        fp = stdin;
1.13      tedu       90:                } else {
1.18    ! schwarze   91:                        if ((fp = fopen(*argv, "r")) == NULL) {
1.5       aaron      92:                                warn("%s", *argv++);
1.17      tedu       93:                                status = 1;
1.4       aaron      94:                                continue;
1.1       deraadt    95:                        }
                     96:                        if (argc > 1) {
                     97:                                if (!firsttime)
                     98:                                        putchar('\n');
                     99:                                printf("==> %s <==\n", *argv);
                    100:                        }
                    101:                        ++argv;
                    102:                }
1.18    ! schwarze  103:                for (cnt = linecnt; cnt && !feof(fp); --cnt)
        !           104:                        while ((ch = getc(fp)) != EOF)
1.1       deraadt   105:                                if (putchar(ch) == '\n')
                    106:                                        break;
1.18    ! schwarze  107:                fclose(fp);
1.1       deraadt   108:        }
                    109:        /*NOTREACHED*/
                    110: }
                    111:
                    112:
                    113: static void
1.11      deraadt   114: usage(void)
1.1       deraadt   115: {
1.14      jmc       116:        fputs("usage: head [-count | -n count] [file ...]\n", stderr);
1.1       deraadt   117:        exit(1);
                    118: }