You can use stat 'Filemane' this returns a 13 element list giving the statistics
for the file "Filename" so

    @res = stat "file_to_stat";
    print qq($res[7]\n);
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will return the size of the file in bytes, the other elements of the list are as follows

    dev - Device number
    ino - Inode number
    mode - File node (type and permissions)
    nlink - No of hard links
    uid - File owner
    gid - Group Id
    rdev - Device identifier
    size - size in bytes
    atime - access time
    mtime - modified time
    ctime - Inode change time
    blksize - Prefered block size
    blocks - actual number of blocks allocated
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Note: Not all fields are supported bt all OSs.
Hope this is of help