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#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
int main(int argc, char *argv[])
{
struct stat st;
char buf[1024];
int len, fd;
if (argc != 2) {
fprintf(stderr, "Usage: %s <iface>\n", argv[0]);
return 1;
}
snprintf(buf, sizeof(buf), "/sys/class/backlight/%s/brightness", argv[1]);
fd = open(buf, O_RDWR);
if (fd < 0 || fstat(fd, &st) || major(st.st_dev)) {
fprintf(stderr, "Cannot access backlight interface '%s'\n", argv[1]);
return 1;
}
while (fgets(buf, sizeof(buf), stdin)) {
len = strlen(buf);
if (write(fd, buf, len) != len) {
fprintf(stderr, "Failed to update backlight interface '%s'\n", argv[1]);
return 2;
}
}
return 0;
}
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