access

 NAME
  access  - determine whether file is accessable

 SYNOPSIS
  int r = access(filename, mode);
  const char *filename;
  int mode;

  UNIX call

 FUNCTION
  Returns 0 on success, -1 if no access with the requested modes
  may be gained.  filename is a pointer to a string that is
  the filename we wish to check, modes is a set of modes we
  expect the file to be able to do.

  the modes may be one or more of the following OR'd together.

  0   check for existance of file only
  1   check execute permission for file
  2   check write permission for file
  4   check read permission for file

 EXAMPLE
  /*
   *  P.S. this is a dumb, slow, inefficient example
   */

  #include <stdio.h>

  main(ac, av)
  char *av[];
  {
      char *name;

      if (ac == 1) {
      puts("Expected a file argument");
      exit(1);
      }
      name = av[1];

      if (access(name, 0) == 0) {
      puts("it exists");
      if (access(name, 1) == 0)
          puts("it is executable");
      if (access(name, 2) == 0)
          puts("I can write to it!");
      if (access(name, 4) == 0)
          puts("and even read from it!");
      } else {
      puts("Hmmm, that file does not exist");
      }
      return(0);
  }

 INPUTS
  char *filename;     file to check
  int mode;       modes as specified above

 RESULTS
  int r;          0 if modes available, -1 if not

 SEE ALSO
  open, fopen