File Operations

1. Exercise: Changing file access attributes:
   • Create a file:

      ceng328@cankaya$ touch foo
     

   • Compile and execute the following code:

     #include <sys/stat.h>
     int main()
     {
       // Create a stat structure for file information
       struct stat buf;
     
       // Take away all available rights from file
       chmod("foo", 0);
     
       // Give read rights for everyone and and execute right
       // for the owner
       chmod("foo", S_IRUSR | S_IRGRP | S_IROTH | S_IXUSR);
     
       // Take away read right from other users
       stat("foo", &buf);
       chmod("foo", buf.st_mode ^ S_IROTH);
     
       // Print current file access rights
       stat("foo", &buf);
       printf("foo - %4.4o\n", buf.st_mode & 07777);
     
       return 0;
     }
     

   • Give this file the following access rights:
     • r w x r - x r - x
     • r - - - - - - - -
     • r - x r - x - - -