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File and directory permissions can
be changed using the chmod (change mode) command or with CDE
File Manager. Normally the default permissions for a file or
directory will be adequate for most security needs. There are
times when you will want to change the permissions on a file or
directory. By default, all files are created with permissions that
allow the user category of others to read the file. This
means anyone with a login id can see the contents of the file and
copy it. For classified files and private information, you should
remove the Read permission from the others category.
Shell scripts are another example
where you would want to change permissions. When you create a
shell script file (or any file), the default permissions do not
include execute, even for the owner/creator of the file. To run
the shell script, you must change the permissions by adding the
execute permission as shown in the Figure.
The chmod
command is used by a file's owner (or superuser) to change file
permissions. The two modes of operation with the chmod
command are symbolic
(or relative) and octal (or absolute).
- Symbolic mode - uses
combinations of letters and symbols to add or remove permissions
from various categories of users. Symbolic mode is also referred
to as relative mode.
- Octal mode - uses octal
numbers to represent file permissions. Octal mode is also referred
to as absolute or numeric mode.
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