Linux configuration system

To configure the schema:

Three elements:

Configuration files, environment variables, command-line options

Three levels:

System-level, user-level, program-level

Application:

Configuration information that may change when invoked, using command-line options; The configuration information that is rarely changed but should be controlled by individual users, using user profiles or user environment variables, and system configuration files or system environment variables that need to be set by the system administrator without the user changing the overall system-level configuration information.

Configuration file:

System configuration file:

/etc/<config-file>

/etc/<config-folder>/...

User profiles: typically hidden files

~/<config-file>

~/<config-folder>/...

Named:

How to add an "rc" suffix after using the executable file name

RC indicates operation control

Environment variables:

System-Level environment variables

$HOME, $USER

User-level environment variables

Command-Line options:

Original UNIX-style command-line options:

The option is a single letter that begins with the hyphen "-", and if the option is followed by a modal option, the pattern option can be combined, and if the option has parameters, the parameter should be immediately following the option.

GNU-style command-line options:

The option is followed by a two consecutive hyphen "-" after the option keyword;

X Toolkit Style command-line options:

Linux configuration system