Table of contents
ACL PERMISSION
Access Control Lists (ACLs) are essentially a set of rules that specify who can access which files and directories under Linux. Consider having a room filled with various possessions and wanting to manage who has access to them and what they can be used for.
under this situation, read, write, and execute permissions are among the permissions that each file or directory under Linux has. ACLs offer a mechanism to go beyond these fundamental permissions, though. They give you more granular control over who can do what by enabling you to grant or reject particular permissions to individual users or groups.
For example, let's say you have a file called "file1.txt." By default, only the owner of the file has full control over it. However, with ACLs, you can grant read access to other users or groups, allowing them to view the contents of the file. You can also give write access to certain individuals, allowing them to modify the file while restricting others from making any changes.
ACLs give you the flexibility to define custom permissions for different users or groups, allowing for more precise control over access to your files and directories. They make it easier to manage file permissions in complex scenarios and ensure that the right people have the right level of access to your data.
EXAMPLE FOR $getfacl
$ getfacl file1.txt
EXAMPLE FOR $setfacl
$ setfacl -m u:user1:rw file1.txt
HELP COMMANDS IN LINUX:
Help commands are there to assist you in understanding and using different commands in Linux. They provide various levels of information, from detailed documentation to quick summaries, making it easier for you to learn and utilize the power of the Linux command line.
Here are simplified explanations of the help commands in Linux:
$man: The man command stands for "manual." It provides detailed documentation for other commands. Think of it as a comprehensive guidebook that explains how to use different commands. You can look up a specific command and find information on its usage, options, and examples.$--help: Many commands in Linux have a help option. It gives you a quick summary of how to use a command and what options are available. It's like a cheat sheet that provides concise information without overwhelming you with too much detail.$info: The info command is similar to man but it provides more in-depth documentation on various commands, utilities, and topics. It's like an extensive textbook that covers a wide range of subjects. You can navigate through different sections and find detailed explanations about specific commands or concepts.$whatis: The whatis command gives you a brief description of a command or utility. It provides a simple, one-line explanation to help you quickly understand what a command does. It's like a concise summary or a sneak peek into the purpose of a particular command.
TAB COMPLETION:
By using the Tab key, you may use Linux's useful tab completion feature to finish commands, file names, and directory paths. The system automatically recommends potential completions based on what you've entered so far when you begin typing a command or file/directory name and click Tab. You spend less time typing and are less likely to make mistakes.
For instance, to use the cat command to list the contents of a file with the name "document.txt" in your current directory, start typing $cat doc and then hit Tab. Your file name will be completed by the system, which will produce the result cat document.txt. If there are several alternatives, pressing Tab again will show you a list of them.
Tab completion also works for command options and parameters. If you're not sure about the available options for a command, you can type the command followed by a dash (-) and then press Tab. The system will show you the available options, allowing you to select the one you need.
UP-ARROW:
In Linux, you may go back and type earlier commands in the terminal by pressing the Up Arrow key. It enables you to navigate through your command history, making it simple to reuse or edit earlier commands without having to completely retype them.
For instance, you may just press the Up Arrow key to bring up the most recent command in your history if you conducted a complicated command in the past and wish to run it again. The Up Arrow key can be used to frequently cycle through previous commands.
Before performing recalled commands, you can also make changes to them. The Left and Right Arrow keys let you move around the command and adjust things as necessary.