symbolic link and readlink system call

gistfile1.txt

man 2 readlink

gistfile2.txt

freedom@debian:~/C$ ls -al /dev/block
total 0
drwxr-xr-x  2 root root  480 Jan 29 22:26 .
drwxr-xr-x 14 root root 3500 Jan 29 22:27 ..
lrwxrwxrwx  1 root root    6 Jan 29 22:26 11:0 -> ../sr0
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:0 -> ../loop0
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:1 -> ../loop1
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:2 -> ../loop2
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:3 -> ../loop3
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:4 -> ../loop4
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:5 -> ../loop5
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:6 -> ../loop6
lrwxrwxrwx  1 root root    8 Jan 29 22:26 7:7 -> ../loop7
lrwxrwxrwx  1 root root    6 Jan 29 22:26 8:0 -> ../sda
lrwxrwxrwx  1 root root    7 Jan 29 22:26 8:1 -> ../sda1
lrwxrwxrwx  1 root root    6 Jan 29 22:26 8:16 -> ../sdb
lrwxrwxrwx  1 root root    7 Jan 29 22:26 8:2 -> ../sda2
lrwxrwxrwx  1 root root    7 Jan 29 22:26 8:3 -> ../sda3
lrwxrwxrwx  1 root root    6 Jan 29 22:26 8:32 -> ../sdc
lrwxrwxrwx  1 root root    7 Jan 29 22:26 8:4 -> ../sda4
lrwxrwxrwx  1 root root    6 Jan 29 22:26 8:48 -> ../sdd
lrwxrwxrwx  1 root root    7 Jan 29 22:26 8:5 -> ../sda5
lrwxrwxrwx  1 root root    7 Jan 29 22:26 8:6 -> ../sda6
lrwxrwxrwx  1 root root    6 Jan 29 22:26 8:64 -> ../sde
lrwxrwxrwx  1 root root    7 Jan 29 22:26 8:7 -> ../sda7
lrwxrwxrwx  1 root root    6 Jan 29 22:26 8:80 -> ../sdf

symlink-test.c

#include <errno.h>
#include <stdio.h>
#include <unistd.h>

int main (int argc, char* argv[])
{
 char target_path[256];
 char* link_path = argv[1];

 /* Attempt to read the target of the symbolic link. */
 int len = readlink (link_path, target_path, sizeof (target_path));

 if (len == -1) {
  /* The call failed. */
  if (errno == EINVAL)
   /* It's not a symbolic link; report that. */
   fprintf (stderr, "%s is not a symbolic link\n", link_path);
  else
   /* Some other problem occurred; print the generic message. */
   perror ("readlink");
  return 1;
 }
 else {
  /* NUL-terminate the target path. */
  target_path[len] = '\0';
  /* Print it. */
  printf ("%s\n", target_path);
  return 0;
 }
}