Linux System: Basic Operations and Management

12006

1. What is Linux System

Linux is an open-source operating system widely used in servers, desktop computers, mobile devices, and embedded systems. The Linux system is known for its high security and stability, excelling in handling multitasking and a large number of concurrent requests. This makes it an ideal choice for running servers, high-performance computing, and big data processing. Debian is one of the distributions of Linux.

2. Understanding the Linux File System

The Linux file system is a way to organize and store files, defining how files are stored and retrieved on the disk. Linux follows the philosophy of "everything is a file." Almost everything, including hardware devices and processes, is treated as a file. This means you can interact with these "files" using standard file operation commands.

Linux uses a hierarchical directory structure. The top level of the file system is the root directory, represented as "/". All other files and directories start from the root directory.

The main directories in Linux include:

/bin: Contains essential binary executable files that are critical for system boot and operation.
/boot: Contains files required to boot Linux, including the Linux kernel.
/dev: Contains device files.
/etc: Contains system configuration files.
/home: Contains personal folders for regular users.
/lib: Contains library files required by the system and applications.
/media and /mnt: Used to mount (connect) external devices, such as hard drives and CD-ROMs.
/opt: Typically contains optional application software packages.
/proc: A virtual file system that contains information about the running kernel and processes.
/root: The home directory of the system administrator (root user).
/sbin: Contains system administration commands.
/tmp: Used to store temporary files.
/usr: The main storage area for user programs and data, such as system default applications and libraries.
/var: Contains files that change frequently, such as log files.

The Linux file system has explicit permission and ownership settings for each file and directory. This includes read (r), write (w), and execute (x) permissions, set for the file/directory owner, group, and other users.

3. Common Linux Commands

The Linux operating system provides a wealth of command-line tools that enable users to interact effectively with the system. Here are some basic and commonly used Linux commands:

File and Directory Operation Commands:

ls: List files and subdirectories in the current directory.
cd: Change to the specified directory.
pwd: Display the path of the current directory.
mkdir: Create a new directory.
rm: Remove files or directories.
cp: Copy files or directories.
mv: Move files or directories.

System Operation Commands:

ps: View the currently running processes in the system.
top: Display real-time resource usage of various processes in the system.
kill: Terminate a specified process.
reboot: Restart the system.
shutdown: Power off the system.

Network Operation Commands:

ping: Test network connectivity.
wget: Download files from the internet.
curl: A more powerful tool for downloading files from the internet.
ifconfig: View the configuration information of network interfaces.
netstat: View the status of network connections.

Other Commands:

grep: Search for a specified string in files.
sed: A text editor that can perform string replacement and other operations.
tar: Package and compress files.
ssh: Remotely log in to another computer.
scp: Transfer files between local and remote computers.

Assignment

Try out the Linux commands learned in this lesson on the server.

## 1. What is Linux System

Linux is an open-source operating system widely used in servers, desktop computers, mobile devices, and embedded systems. The Linux system is known for its high security and stability, excelling in handling multitasking and a large number of concurrent requests. This makes it an ideal choice for running servers, high-performance computing, and big data processing. Debian is one of the distributions of Linux.

## 2. Understanding the Linux File System

The Linux file system is a way to organize and store files, defining how files are stored and retrieved on the disk. Linux follows the philosophy of "everything is a file." Almost everything, including hardware devices and processes, is treated as a file. This means you can interact with these "files" using standard file operation commands.

Linux uses a hierarchical directory structure. The top level of the file system is the root directory, represented as "/". All other files and directories start from the root directory.

The main directories in Linux include:
- /bin: Contains essential binary executable files that are critical for system boot and operation.
- /boot: Contains files required to boot Linux, including the Linux kernel.
- /dev: Contains device files.
- /etc: Contains system configuration files.
- /home: Contains personal folders for regular users.
- /lib: Contains library files required by the system and applications.
- /media and /mnt: Used to mount (connect) external devices, such as hard drives and CD-ROMs.
- /opt: Typically contains optional application software packages.
- /proc: A virtual file system that contains information about the running kernel and processes.
- /root: The home directory of the system administrator (root user).
- /sbin: Contains system administration commands.
- /tmp: Used to store temporary files.
- /usr: The main storage area for user programs and data, such as system default applications and libraries.
- /var: Contains files that change frequently, such as log files.

The Linux file system has explicit permission and ownership settings for each file and directory. This includes read (r), write (w), and execute (x) permissions, set for the file/directory owner, group, and other users.

## 3. Common Linux Commands

The Linux operating system provides a wealth of command-line tools that enable users to interact effectively with the system. Here are some basic and commonly used Linux commands:

**File and Directory Operation Commands:**

- `ls`: List files and subdirectories in the current directory.
- `cd`: Change to the specified directory.
- `pwd`: Display the path of the current directory.
- `mkdir`: Create a new directory.
- `rm`: Remove files or directories.
- `cp`: Copy files or directories.
- `mv`: Move files or directories.

**System Operation Commands:**

- `ps`: View the currently running processes in the system.
- `top`: Display real-time resource usage of various processes in the system.
- `kill`: Terminate a specified process.
- `reboot`: Restart the system.
- `shutdown`: Power off the system.

**Network Operation Commands:**

- `ping`: Test network connectivity.
- `wget`: Download files from the internet.
- `curl`: A more powerful tool for downloading files from the internet.
- `ifconfig`: View the configuration information of network interfaces.
- `netstat`: View the status of network connections.

**Other Commands:**

- `grep`: Search for a specified string in files.
- `sed`: A text editor that can perform string replacement and other operations.
- `tar`: Package and compress files.
- `ssh`: Remotely log in to another computer.
- `scp`: Transfer files between local and remote computers.

## Assignment

- Try out the Linux commands learned in this lesson on the server.