perldoc -f stat

     stat FILEHANDLE
     stat EXPR
     stat    Returns a 13-element list giving the status info for
             a file, either the file opened via FILEHANDLE, or
             named by EXPR.  If EXPR is omitted, it stats $_.
             Returns a null list if the stat fails.  Typically
             used as follows:

                 ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
                    $atime,$mtime,$ctime,$blksize,$blocks)
                        = stat($filename);

             Not all fields are supported on all filesystem
             types.  Here are the meanings of the fields:

               0 dev      device number of filesystem
               1 ino      inode number
               2 mode     file mode  (type and permissions)
               3 nlink    number of (hard) links to the file
               4 uid      numeric user ID of file's owner
               5 gid      numeric group ID of file's owner
               6 rdev     the device identifier (special files only)
               7 size     total size of file, in bytes
               8 atime    last access time in seconds since the epoch
               9 mtime    last modify time in seconds since the epoch
              10 ctime    inode change time in seconds since the epoch
+ (*)
              11 blksize  preferred block size for file system I/O
              12 blocks   actual number of blocks allocated
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open MYFILE, '<filename' or die "Can not open: $!";
my $uid = (stat MYFILE)[4];
close MYFILE;

print "UID = $uid\n";
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