File Names

• 1 to 255 characters long,
• Lower case and upper case characters are different.
  Example : file.txt and File.txt are different files.
• File names can contain any character but "/".

However, file names should only contain the following characters:
"a", ... "z", "A", ... "Z", "0", ... "9", "-", "_", "." because:

• Many characters have special meaning for the shell, and must be "escaped" with a preceding "\".
• Using only ASCII characters, file names remain the same across operating systems and and whatever the character set used.

For example, in a graphical user interface, one can click on a file name which contains a space character; but in a shell, such a file has to be written file\ name\ with\ spaces.txt or "file name with spaces.txt" or 'file name with spaces.txt'.