D -- Directory. The presence of this letter means that the file is a directory. It

is set when the file is created and can not be changed. Directory files may not be

loaded or run.

E -- Execute. If this letter is present, the (non-directory) file may not be loaded

or read in any way, but only executed. The commands which will operate on an

execute-only file are *RUN, */, *ACCESS, *DELETE, *REMOVE and

*DESTROY. Once the 'E' has been set it can not be removed, and the only other

letter which may be changed is 'L' (see below). *INFO produces the minimum of

information about such files.

L -- Locked. Locked files cannot be deleted using *DELETE, *REMOVE or

*DESTROY, nor may they be renamed with *RENAME or overwritten in any

way (see below). Any attempt to do any of these things without first removing

the 'L' code using *ACCESS will result in the error message 'Locked'.

Directories have 'L' set by default when they are created, and files may have it

set or removed by the user.

R -- Read. Only if this character is present may any information be read from

the file; it is unlikely to be changed by most users since usually you do want to

read your files. You can not remove the 'R' access character from a directory.

W--- Write. This character determines whether information may be written to

the file; if it is not present, the file may be neither written to nor altered in any

way (note, however, that the 'L' character must be set to prevent the file from

being deleted). Directories cannot have the 'W' character set.

The *ACCESS command allows a file's access code characters to be changed; it

needs to be followed first by a pathname (wildcards allowed) and second by the

access codes to be applied to the matching files. Examples include:

*ACCESS test Remove all access except 'D' and 'E' from 'test'.

*ACCESS * LR Protect all files in the CSD from overwriting and deletion

*ACCESS Letters.* WR Make all files in 'letters' readable and writable.

The most common applications of access codes are

to set 'L' to prevent accidental deletion, to unset

'L' to allow intentional deletion and to unset 'W' to

prevent overwriting.

Deleting, renaming and copying files

When a file is no longer required, it should be deleted from the disc. This makes

the space it previously occupied free for use by other files, reducing the

likelihood of the disc becoming full. The *DELETE command removes a single

named file from a directory; the filename must not contain any wildcards. For

example:

F 16