php -n -r 'fseek(fopen("/dev/zero", "rb"), 1*1024*1024, SEEK_SET);'

Warning: fseek(): Stream does not support seeking in Command line code on line 1

#include <stdio.h>
#include <stdlib.h>
int main(void) {
 FILE *fp = fopen("/dev/zero", "rb");
 if (fp == NULL) {
 perror("Failed to open /dev/zero");
 return EXIT_FAILURE;
 }
 if (fseek(fp, 1024 * 1024, SEEK_CUR) != 0) {
 perror("Failed to fseek to 1MB");
 fclose(fp);
 return EXIT_FAILURE;
 }
 int c = fgetc(fp);
 if (c == EOF) {
 if (ferror(fp)) {
 perror("Error reading from /dev/zero");
 } else {
 fprintf(stderr, "Unexpected EOF on /dev/zero\n");
 }
 fclose(fp);
 return EXIT_FAILURE;
 }
 if (putchar(c) == EOF) {
 perror("Failed to write to stdout");
 fclose(fp);
 return EXIT_FAILURE;
 }
 if (fclose(fp) != 0) {
 perror("Failed to close /dev/zero");
 return EXIT_FAILURE;
 }
 return EXIT_SUCCESS;
}

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
int main(void) {
 int fd = open("/dev/zero", O_RDONLY);
 if (fd == -1) {
 perror("Failed to open /dev/zero");
 return EXIT_FAILURE;
 }
 // Seek forward 1MB
 if (lseek(fd, 1024 * 1024, SEEK_CUR) == (off_t)-1) {
 perror("Failed to lseek to 1MB");
 close(fd);
 return EXIT_FAILURE;
 }
 unsigned char c;
 ssize_t n = read(fd, &c, 1);
 if (n == -1) {
 perror("Error reading from /dev/zero");
 close(fd);
 return EXIT_FAILURE;
 } else if (n == 0) {
 fprintf(stderr, "Unexpected EOF on /dev/zero\n");
 close(fd);
 return EXIT_FAILURE;
 }
 if (write(STDOUT_FILENO, &c, 1) == -1) {
 perror("Failed to write to stdout");
 close(fd);
 return EXIT_FAILURE;
 }
 if (close(fd) == -1) {
 perror("Failed to close /dev/zero");
 return EXIT_FAILURE;
 }
 return EXIT_SUCCESS;
}

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