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 C.3.3.1 Using `chdir()' and `stat()'
 ....................................
 
 This minor node shows how to use the new functions at the `awk' level
 once they've been integrated into the running `gawk' interpreter.
 Using `chdir()' is very straightforward. It takes one argument, the new
 directory to change to:
 
      ...
      newdir = "/home/arnold/funstuff"
      ret = chdir(newdir)
      if (ret < 0) {
          printf("could not change to %s: %s\n",
                         newdir, ERRNO) > "/dev/stderr"
          exit 1
      }
      ...
 
    The return value is negative if the `chdir' failed, and `ERRNO'
 ( Built-in Variables) is set to a string indicating the error.
 
    Using `stat()' is a bit more complicated.  The C `stat()' function
 fills in a structure that has a fair amount of information.  The right
 way to model this in `awk' is to fill in an associative array with the
 appropriate information:
 
      file = "/home/arnold/.profile"
      fdata[1] = "x"    # force `fdata' to be an array
      ret = stat(file, fdata)
      if (ret < 0) {
          printf("could not stat %s: %s\n",
                   file, ERRNO) > "/dev/stderr"
          exit 1
      }
      printf("size of %s is %d bytes\n", file, fdata["size"])
 
    The `stat()' function always clears the data array, even if the
 `stat()' fails.  It fills in the following elements:
 
 `"name"'
      The name of the file that was `stat()''ed.
 
 `"dev"'
 `"ino"'
      The file's device and inode numbers, respectively.
 
 `"mode"'
      The file's mode, as a numeric value. This includes both the file's
      type and its permissions.
 
 `"nlink"'
      The number of hard links (directory entries) the file has.
 
 `"uid"'
 `"gid"'
      The numeric user and group ID numbers of the file's owner.
 
 `"size"'
      The size in bytes of the file.
 
 `"blocks"'
      The number of disk blocks the file actually occupies. This may not
      be a function of the file's size if the file has holes.
 
 `"atime"'
 `"mtime"'
 `"ctime"'
      The file's last access, modification, and inode update times,
      respectively.  These are numeric timestamps, suitable for
      formatting with `strftime()' ( Built-in).
 
 `"pmode"'
      The file's "printable mode."  This is a string representation of
      the file's type and permissions, such as what is produced by `ls
      -l'--for example, `"drwxr-xr-x"'.
 
 `"type"'
      A printable string representation of the file's type.  The value
      is one of the following:
 
     `"blockdev"'
     `"chardev"'
           The file is a block or character device ("special file").
 
     `"directory"'
           The file is a directory.
 
     `"fifo"'
           The file is a named-pipe (also known as a FIFO).
 
     `"file"'
           The file is just a regular file.
 
     `"socket"'
           The file is an `AF_UNIX' ("Unix domain") socket in the
           filesystem.
 
     `"symlink"'
           The file is a symbolic link.
 
    Several additional elements may be present depending upon the
 operating system and the type of the file.  You can test for them in
 Elements::):
 
 `"blksize"'
      The preferred block size for I/O to the file. This field is not
      present on all POSIX-like systems in the C `stat' structure.
 
 `"linkval"'
      If the file is a symbolic link, this element is the name of the
      file the link points to (i.e., the value of the link).
 
 `"rdev"'
 `"major"'
 `"minor"'
      If the file is a block or character device file, then these values
      represent the numeric device number and the major and minor
      components of that number, respectively.
 

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