81 lines
1.2 KiB
C
81 lines
1.2 KiB
C
/* head.c */
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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/* head */
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static int _head_do(int flgn, char * filename);
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static int _head(int flgn, int argc, char * argv[])
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{
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int res = 0;
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int i;
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if(argc == 0)
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return _head_do(flgn, NULL);
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for(i = 0; i < argc; i++)
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{
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if(_head_do(flgn, argv[i]) != 0)
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res = 2;
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}
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return res;
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}
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static int _head_do(int flgn, char * filename)
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{
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FILE * fp;
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int n = 0;
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int c;
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if(filename == NULL)
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fp = stdin;
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else if((fp = fopen(filename, "r")) == NULL)
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{
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perror(filename);
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return 1;
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}
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while((c = fgetc(fp)) != EOF && n < flgn)
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{
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if(c == '\n')
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n++;
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fwrite(&c, sizeof(char), 1, stdout);
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}
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if(filename != NULL)
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fclose(fp);
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return 0;
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}
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/* usage */
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static int _usage(void)
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{
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fprintf(stderr, "%s", "Usage: head [-n number][file...]\n\
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-n print first number lines on standard output\n");
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return 1;
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}
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/* main */
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int main(int argc, char* argv[])
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{
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int flgn = 10;
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int o;
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char * p;
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while((o = getopt(argc, argv, "n:")) != -1)
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switch(o)
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{
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case 'n':
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flgn = strtol(optarg, &p, 10);
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if(*optarg == '\0' || *p != '\0')
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return _usage();
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break;
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default:
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return _usage();
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}
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return _head(flgn, argc - optind, &argv[optind]);
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}
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