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Annotation of 43BSDTahoe/ucb/head.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1980, 1987 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that the above copyright notice and this paragraph are
        !             7:  * duplicated in all such forms and that any documentation,
        !             8:  * advertising materials, and other materials related to such
        !             9:  * distribution and use acknowledge that the software was developed
        !            10:  * by the University of California, Berkeley.  The name of the
        !            11:  * University may not be used to endorse or promote products derived
        !            12:  * from this software without specific prior written permission.
        !            13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            16:  */
        !            17: 
        !            18: #ifndef lint
        !            19: char copyright[] =
        !            20: "@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\
        !            21:  All rights reserved.\n";
        !            22: #endif /* not lint */
        !            23: 
        !            24: #ifndef lint
        !            25: static char sccsid[] = "@(#)head.c     5.4 (Berkeley) 6/29/88";
        !            26: #endif /* not lint */
        !            27: 
        !            28: #include <stdio.h>
        !            29: #include <ctype.h>
        !            30: /*
        !            31:  * head - give the first few lines of a stream or of each of a set of files
        !            32:  *
        !            33:  * Bill Joy UCB August 24, 1977
        !            34:  */
        !            35: 
        !            36: main(argc, argv)
        !            37:        int     argc;
        !            38:        char    **argv;
        !            39: {
        !            40:        register int    ch, cnt;
        !            41:        int     firsttime, linecnt = 10;
        !            42: 
        !            43:        if (argc > 1 && argv[1][0] == '-') {
        !            44:                if (!isdigit(argv[1][1])) {
        !            45:                        fprintf(stderr, "head: illegal option -- %c\n", argv[1][1]);
        !            46:                        goto usage;
        !            47:                }
        !            48:                if ((linecnt = atoi(argv[1] + 1)) < 0) {
        !            49: usage:                 fputs("usage: head [-line_count] [file ...]\n", stderr);
        !            50:                        exit(1);
        !            51:                }
        !            52:                --argc; ++argv;
        !            53:        }
        !            54:        /* setlinebuf(stdout); */
        !            55:        for (firsttime = 1, --argc, ++argv;; firsttime = 0) {
        !            56:                if (!*argv) {
        !            57:                        if (!firsttime)
        !            58:                                exit(0);
        !            59:                }
        !            60:                else {
        !            61:                        if (!freopen(*argv, "r", stdin)) {
        !            62:                                fprintf(stderr, "head: can't read %s.\n", *argv);
        !            63:                                exit(1);
        !            64:                        }
        !            65:                        if (argc > 1) {
        !            66:                                if (!firsttime)
        !            67:                                        putchar('\n');
        !            68:                                printf("==> %s <==\n", *argv);
        !            69:                        }
        !            70:                        ++argv;
        !            71:                }
        !            72:                for (cnt = linecnt; cnt; --cnt)
        !            73:                        while ((ch = getchar()) != EOF)
        !            74:                                if (putchar(ch) == '\n')
        !            75:                                        break;
        !            76:        }
        !            77:        /*NOTREACHED*/
        !            78: }

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