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Annotation of 43BSDTahoe/ucb/head.c, revision 1.1.1.1

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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