How to troubleshoot in Linux?

Boot Issues: Check boot logs (dmesg, journalctl -xb), bootloader configuration (grub.cfg).

Networking: Verify network configuration (ifconfig, ip addr), check connectivity (ping, traceroute), review firewall settings (iptables).

Performance: Monitor system resources (top, htop, vmstat), check disk usage (df -h), identify CPU or memory bottlenecks.

Disk Space: Check disk usage (df -h), identify large files/directories (du -sh).
Permissions: Verify file/directory permissions (ls -l, getfacl), ensure correct ownership (chown, chgrp).

Software Installation: Check package installation (dpkg, rpm, apt, yum), verify dependencies.
Service Management: Restart services (systemctl restart <service>), check service status (systemctl status <service>).

Logging and Monitoring: Review system logs (/var/log), use monitoring tools (sar, sysstat, Prometheus, Grafana).

Hardware and Drivers: Check hardware status (lspci, lsusb), verify driver status (lsmod, modprobe).

User and Group Management: Verify user permissions (groups, id), manage user accounts (adduser, usermod, deluser).

• dmesg – Displays the kernel ring buffer messages.
• journalctl – Views and manages systemd journal logs.
• ls – Lists directory contents.
• ps – Lists currently running processes.
• top – Displays real-time system information, including CPU and memory usage.
• htop – Interactive process viewer and system monitor.
• df – Shows disk space usage.
• du – Displays disk usage for files and directories.
• free – Shows memory and swap usage.
• uptime – Displays system uptime and load averages.
• netstat – Shows network statistics, connections, and routing tables.
• ifconfig – Displays network interface configuration.
• ip – Shows or manipulates routing, devices, policy routing, and tunnels.
• ping – Sends ICMP Echo Request packets to a network host.
• traceroute – Prints the route packets take to a network host.
• lsof – Lists open files and the processes that opened them.
• ps – Lists information about processes.
• kill – Sends a signal to terminate processes.
• systemctl – Controls systemd services (e.g., start, stop, enable, disable).
• grep – Searches for patterns in files or input.
• tail – Outputs the last part of files.
• cat – Concatenates and displays files.
• less – Displays text files with pagination.
• find – Searches for files and directories.
• cp – Copies files and directories.
• mv – Moves or renames files and directories.
• rm – Removes files and directories.
• chmod – Changes file permissions.
• chown – Changes file owner and group.
• ssh – Securely connects to a remote server.