Basic format for command 'open':
    vitis-sl open [[-e][-v]] <input data> [options]

Opening files by expression:
    vitis-sl open [-e] <expression> [options] ...

This command opens files from the expression using programs by default.
If utility 'ufo' is installed on the system,
the task of determining the opening programs is delegated to it
(unless otherwise specified in settings).

Flag '-n' is used to select one or a series of files.
If there is a number after the '-n' flag, one file will be displayed.
Also, after the '-n' flag, you can use an expression that lists the numbers
of the files you need and ranges of files using a dash,
separated by commas without spaces.

Flag --sort=<sorting> is used to specify the sorting type:
     --sort=extension - sort by file extension;
     --sort=name      - sort by file name (default);
     --sort=none      - without sorting;
     --sort=size      - sort by file size;
     --sort=time      - sort by file modification time;
     --sort=atime     - sort by file access time.

Option '--hidden' enables the use of hidden files.

Option '-app' allows to select an alternative program to open the files.
    Example:
    vitis-sl open Music --app vlc
        Files from 'Music' category will be opened in the VLC player.

Option '--saved-page' allows to open local copies of saved HTML pages,
if they exist.

Option '--mix' causes the file list to randomly intermix.

Option '--reverse' reverses the sort order.

Opening by name in vitis-sl:
    vitis-sl open -v <category/file> [options]

A simpler and more accurate way to open a file is by its name and category.

The options '--app', '--saved-page' are applicable to this command.

Additional option '--number' allows you to specify the number of the file with
repeated name.
