root / prex-0.9.0 / usr / bin / head / head.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*
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2 | * Copyright (c) 1980, 1987, 1992, 1993
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3 | * The Regents of the University of California. All rights reserved.
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4 | *
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5 | * Redistribution and use in source and binary forms, with or without
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6 | * modification, are permitted provided that the following conditions
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7 | * are met:
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8 | * 1. Redistributions of source code must retain the above copyright
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9 | * notice, this list of conditions and the following disclaimer.
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10 | * 2. Redistributions in binary form must reproduce the above copyright
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11 | * notice, this list of conditions and the following disclaimer in the
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12 | * documentation and/or other materials provided with the distribution.
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13 | * 3. Neither the name of the University nor the names of its contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | */
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29 | |||
30 | #include <sys/types.h> |
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31 | |||
32 | #include <ctype.h> |
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33 | #include <err.h> |
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34 | #include <errno.h> |
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35 | #include <stdio.h> |
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36 | #include <stdlib.h> |
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37 | #include <string.h> |
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38 | #include <unistd.h> |
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39 | |||
40 | /*
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41 | * head - give the first few lines of a stream or of each of a set of files
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42 | *
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43 | * Bill Joy UCB August 24, 1977
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44 | */
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45 | |||
46 | #ifdef CMDBOX
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47 | #define main(argc, argv) head_main(argc, argv)
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48 | #endif
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49 | |||
50 | void head(FILE *, int); |
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51 | static void usage(void); |
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52 | |||
53 | int eval;
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54 | |||
55 | int
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56 | main(int argc, char *argv[]) |
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57 | { |
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58 | int ch;
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59 | FILE *fp; |
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60 | int first, linecnt;
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61 | char *ep;
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62 | |||
63 | linecnt = 10;
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64 | while ((ch = getopt(argc, argv, "n:")) != EOF) |
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65 | switch(ch) {
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66 | case 'n': |
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67 | linecnt = strtol(optarg, &ep, 10);
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68 | if (*ep || linecnt <= 0) |
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69 | err(1, "illegal line count -- %s", optarg); |
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70 | break;
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71 | case '?': |
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72 | default:
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73 | usage(); |
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74 | } |
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75 | argc -= optind; |
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76 | argv += optind; |
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77 | |||
78 | if (*argv)
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79 | for (first = 1; *argv; ++argv) { |
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80 | if ((fp = fopen(*argv, "r")) == NULL) { |
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81 | err(0, "%s: %s", *argv, strerror(errno)); |
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82 | continue;
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83 | } |
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84 | if (argc > 1) { |
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85 | (void)printf("%s==> %s <==\n", |
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86 | first ? "" : "\n", *argv); |
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87 | first = 0;
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88 | } |
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89 | head(fp, linecnt); |
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90 | (void)fclose(fp);
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91 | } |
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92 | else
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93 | head(stdin, linecnt); |
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94 | exit(eval); |
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95 | } |
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96 | |||
97 | void
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98 | head(FILE *fp, int cnt)
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99 | { |
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100 | int ch;
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101 | |||
102 | while (cnt--)
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103 | while ((ch = getc(fp)) != EOF) { |
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104 | if (putchar(ch) == EOF) |
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105 | err(1, "stdout: %s", strerror(errno)); |
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106 | if (ch == '\n') |
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107 | break;
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108 | } |
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109 | } |
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110 | |||
111 | static void |
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112 | usage() |
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113 | { |
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114 | (void)fprintf(stderr, "usage: head [-n lines] [file ...]\n"); |
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115 | exit(1);
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116 | } |