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#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
int
head(int fd, int lines)
{
int a;
ssize_t r;
int c = 0;
while((r = read(fd, &a, 1)) > 0) {
if(r == -1) {
fprintf(stderr, "head: %s\n", strerror(errno));
return 1;
}
if((char)a == '\n')
++c;
putchar(a);
if(c == lines)
break;
}
return 0;
}
int
main(int argc, char *argv[])
{
int lines = 10;
int return_value = 0;
int c, fd;
c = getopt(argc, argv, "n:");
switch(c) {
case 'n':
lines = atoi(optarg);
if(lines == 0) {
fprintf(stderr, "head: invalid number '%s'\n", optarg);
return 1;
}
break;
case ':':
case '?':
fprintf(stderr, "usage: head [-n N] file\n");
return 1;
}
if(optind == argc)
fd = 0;
else {
fd = open(argv[optind], O_RDONLY);
if(fd == -1) {
fprintf(stderr, "head: %s: %s\n", argv[optind], strerror(errno));
return 1;
}
}
return_value = head(fd, lines);
close(fd);
return return_value;
}
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