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Ever wondered what happens when you press the power button on your Linux system? Let’s break it down step by step!
1. Power On
The journey begins when the computer initializes hardware components.
2. BIOS & ROM
The BIOS (Basic Input/Output System), stored in the ROM chip, performs a Power-On Self Test (POST) and locates the bootloader.
Command to check BIOS version (Linux):
sudo dmidecode -t bios
3. Master Boot Record (MBR)
The MBR contains bootloader code and the partition table.
View MBR (Linux):
sudo dd if=/dev/sda bs=512 count=1 | hexdump -C
4. Boot Loader (GRUB)
The bootloader (e.g., GRUB) loads the Linux kernel into memory.
Edit GRUB config:
sudo nano /etc/default/grub
Update GRUB:
sudo update-grub
5. Kernel Initialization
The kernel manages hardware resources and starts essential services.
Check kernel version:
uname -r
6. User Space & System Calls
Applications run in user space and interact with hardware via system calls.
List system calls for a process:
strace -p <PID>
7. Process Management
The kernel schedules processes efficiently.
View running processes:
top
Kill a process:
kill -9 <PID>
8. Device Drivers
Kernel modules handle hardware communication.
List loaded modules:
lsmod
9. File System Management
Linux organizes data using file systems (ext4, XFS, etc.).
Check disk usage:
df -h
10. Shell & GUI
Users interact via the terminal or GUI.
Open a terminal:
gnome-terminal
You Should Know:
- Check boot logs:
journalctl -b
- Monitor systemd services:
systemctl list-units --type=service
- Analyze disk I/O:
iotop
- Test network connectivity:
ping google.com
- Secure SSH access:
sudo nano /etc/ssh/sshd_config
What Undercode Say:
Understanding Linux booting deepens troubleshooting skills. Mastering commands like dmesg, lsblk, and `systemctl` enhances system control. Always verify configurations before applying changes.
Expected Output:
$ uname -r 5.15.0-76-generic
References:
Reported By: Agbai Joseph – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
