1/* head - copy first part of files. */ 2 3/* See Makefile for compilation details. */ 4 5#include "config.h" 6 7#include "bashtypes.h" 8#include "posixstat.h" 9#include "filecntl.h" 10 11#if defined (HAVE_UNISTD_H) 12# include <unistd.h> 13#endif 14 15#include "bashansi.h" 16 17#include <stdio.h> 18#include <errno.h> 19#include "chartypes.h" 20 21#include "builtins.h" 22#include "shell.h" 23#include "bashgetopt.h" 24 25#if !defined (errno) 26extern int errno; 27#endif 28 29static void 30munge_list (list) 31 WORD_LIST *list; 32{ 33 WORD_LIST *l, *nl; 34 WORD_DESC *wd; 35 char *arg; 36 37 for (l = list; l; l = l->next) 38 { 39 arg = l->word->word; 40 if (arg[0] != '-' || arg[1] == '-' || (DIGIT(arg[1]) == 0)) 41 return; 42 /* We have -[0-9]* */ 43 wd = make_bare_word (arg+1); 44 nl = make_word_list (wd, l->next); 45 l->word->word[1] = 'n'; 46 l->word->word[2] = '\0'; 47 l->next = nl; 48 l = nl; /* skip over new argument */ 49 } 50} 51 52static int 53file_head (fp, cnt) 54 FILE *fp; 55 int cnt; 56{ 57 int ch; 58 59 while (cnt--) 60 { 61 while ((ch = getc (fp)) != EOF) 62 { 63 if (putchar (ch) == EOF) 64 { 65 builtin_error ("write error: %s", strerror (errno)); 66 return EXECUTION_FAILURE; 67 } 68 if (ch == '\n') 69 break; 70 } 71 } 72} 73 74head_builtin (list) 75 WORD_LIST *list; 76{ 77 int nline, opt, rval; 78 WORD_LIST *l; 79 FILE *fp; 80 81 char *t; 82 83 munge_list (list); /* change -num into -n num */ 84 85 reset_internal_getopt (); 86 nline = 10; 87 while ((opt = internal_getopt (list, "n:")) != -1) 88 { 89 switch (opt) 90 { 91 case 'n': 92 nline = atoi (list_optarg); 93 if (nline <= 0) 94 { 95 builtin_error ("bad line count: %s", list_optarg); 96 return (EX_USAGE); 97 } 98 break; 99 default: 100 builtin_usage (); 101 return (EX_USAGE); 102 } 103 } 104 list = loptend; 105 106 if (list == 0) 107 return (file_head (stdin, nline)); 108 109 for (rval = EXECUTION_SUCCESS, opt = 1, l = list; l; l = l->next) 110 { 111 fp = fopen (l->word->word, "r"); 112 if (fp == NULL) 113 { 114 builtin_error ("%s: %s", l->word->word, strerror (errno)); 115 continue; 116 } 117 if (list->next) /* more than one file */ 118 { 119 printf ("%s==> %s <==\n", opt ? "" : "\n", l->word->word); 120 opt = 0; 121 } 122 rval = file_head (fp, nline); 123 fclose (fp); 124 } 125 126 return (rval); 127} 128 129char *head_doc[] = { 130 "Copy the first N lines from the input files to the standard output.", 131 "N is supplied as an argument to the `-n' option. If N is not given,", 132 "the first ten lines are copied.", 133 (char *)NULL 134}; 135 136struct builtin head_struct = { 137 "head", /* builtin name */ 138 head_builtin, /* function implementing the builtin */ 139 BUILTIN_ENABLED, /* initial flags for builtin */ 140 head_doc, /* array of long documentation strings. */ 141 "head [-n num] [file ...]", /* usage synopsis; becomes short_doc */ 142 0 /* reserved for internal use */ 143}; 144