the_information_nexus/tech_docs/linux/linux_show.md

General System Information

• hostnamectl: Displays system hostname and identification data.
• lsb_release -a: Provides LSB (Linux Standard Base) information about the distribution.
• cat /etc/os-release: Shows information about the operating system, such as name, version, and ID.
• uname -n: Displays the system's network node hostname.
• uname -r: Shows the kernel release.

Kernel and System Version

• cat /proc/version: Shows the Linux kernel version and related information.
• uname -a: Displays kernel version, architecture, and other system information.
• uname -r: Displays the kernel release version.
• uname -v: Shows the kernel version and build date.
• dmesg | grep -i linux: Displays boot-time messages, which often include kernel version information.

System Uptime and Load

• uptime: Displays system uptime and load averages, useful for monitoring system performance.
• w: Shows who is logged on and their activity, along with system uptime.
• top -n 1 | head -n 10: Provides a quick snapshot of the system's uptime and load without continuous updating.

Hardware Information

• lscpu: Shows detailed information about the CPU architecture.
• lsblk: Lists information about block devices, such as hard drives and their partitions.
• lspci: Lists PCI devices, providing details about internal hardware components.
• lsusb: Lists USB devices connected to the system.
• dmidecode: Outputs hardware information from the BIOS/UEFI, including system manufacturer, model, and serial number.
• free -h: Displays memory usage in a human-readable format.
• inxi -Fxz: Provides comprehensive system information, including hardware, network, and software details (requires installation).

Network Information

• ip addr show: Shows IP addresses and network interfaces.
• netstat -tuln: Displays listening sockets and associated programs, useful for network troubleshooting.
• ss -tuln: Modern alternative to netstat, showing listening sockets and their statuses.
• ifconfig: (Deprecated) Displays network interface information; ip addr is recommended for newer systems.
• ip link show: Shows detailed information about network interfaces.

Disk Usage

• df -h: Shows disk space usage in a human-readable format.
• du -h: Estimates file space usage, providing details on disk usage of files and directories.
• lsblk -f: Displays file system information for each block device.
• df -i: Shows inode usage of file systems.

Process Information

• ps aux: Lists all running processes with detailed information, including user, PID, CPU, and memory usage.
• top: Provides real-time information about running processes and system resources, sorted by CPU usage.
• htop: An interactive version of top with a more user-friendly interface for monitoring processes and system resources.
• pstree: Displays running processes as a tree, showing parent-child relationships.
• pgrep -l : Searches for processes matching a pattern.
• pidstat: Provides detailed statistics on CPU, memory, and I/O usage per process.

Additional Useful Commands

• dmesg | less: Views kernel ring buffer messages.
• journalctl -xe: Views the systemd journal for debugging and log information.
• vmstat: Provides detailed information on system processes, memory, paging, block I/O, traps, and CPU activity.
• iostat: Provides CPU and I/O statistics, useful for identifying bottlenecks.

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Comprehensive Linux System Information Commands

General System Information

• hostnamectl: Displays system hostname and identification data
• lsb_release -a: Provides LSB (Linux Standard Base) information about the distribution
• cat /etc/os-release: Shows operating system information (name, version, ID)
• uname -n: Displays the system's network node hostname

Kernel and System Version

• cat /proc/version: Shows Linux kernel version and compilation details
• uname -a: Displays comprehensive system information (kernel, architecture, hostname)
• uname -r: Shows kernel release version
• uname -v: Displays kernel version with build timestamp
• dmesg | grep -i linux: Shows boot messages containing kernel information

System Uptime and Performance

• uptime: Shows system uptime and load averages (1, 5, 15 minutes)
• w: Displays logged-in users and their activity plus system uptime
• cat /proc/loadavg: Raw load average data
• nproc: Shows number of available processing units

Hardware Information

• lscpu: Detailed CPU architecture and feature information
• lsblk: Lists block devices (drives, partitions) in tree format
• lsblk -f: Includes filesystem information for block devices
• lspci: Lists PCI devices (graphics cards, network adapters, etc.)
• lspci -v: Verbose PCI device information
• lsusb: Lists connected USB devices
• lsusb -v: Verbose USB device details
• dmidecode: Hardware information from BIOS/UEFI (requires root)
• dmidecode -t system: System manufacturer and model info
• free -h: Memory usage in human-readable format
• cat /proc/meminfo: Detailed memory statistics
• lshw: Comprehensive hardware information (may require installation)
• inxi -Fxz: System overview including hardware and software (requires installation)

Storage and Filesystem Information

• df -h: Disk space usage in human-readable format
• df -i: Inode usage statistics
• du -h /path: Directory space usage
• du -sh /path: Summary of directory size
• lsblk -o NAME,SIZE,TYPE,FSTYPE,MOUNTPOINT: Detailed block device info
• findmnt: Shows mounted filesystems in tree format
• blkid: Lists block device UUIDs and filesystem types

Network Information

• ip addr show: Current IP addresses and network interfaces
• ip link show: Network interface details and status
• ip route show: Routing table information
• ss -tuln: Listening sockets (TCP/UDP) - modern netstat replacement
• ss -tulpn: Includes process information for listening sockets
• netstat -tuln: Traditional socket listing (often deprecated)
• netstat -rn: Routing table (traditional command)
• iwconfig: Wireless interface configuration (if available)

Process and Service Information

• ps aux: All running processes with resource usage
• ps -ef: Alternative process listing format
• top: Real-time process monitor (press 'q' to quit)
• htop: Enhanced interactive process viewer (requires installation)
• pstree: Process tree showing parent-child relationships
• pgrep -l pattern: Find processes by name pattern
• pidof process_name: Get PID of specific process
• systemctl list-units --type=service: Active systemd services
• systemctl status service_name: Specific service status

System Monitoring and Performance

• vmstat 1 5: Virtual memory statistics (1-second intervals, 5 samples)
• iostat 1 5: I/O statistics for devices
• iotop: Real-time I/O usage by process (requires installation)
• pidstat 1 5: Per-process statistics
• sar: System activity reporter (part of sysstat package)
• mpstat: Multi-processor usage statistics

Logs and System Messages

• dmesg | less: Kernel ring buffer messages
• dmesg -T: Kernel messages with human-readable timestamps
• journalctl -xe: Recent systemd journal entries with explanations
• journalctl -f: Follow journal in real-time
• journalctl -u service_name: Logs for specific service
• tail -f /var/log/syslog: Follow system log (on systems using syslog)

Environment and Configuration

• env: Display environment variables
• printenv: Alternative to display environment variables
• cat /proc/cmdline: Kernel boot parameters
• lsmod: List loaded kernel modules
• systemctl list-unit-files: All systemd unit files and their states
• crontab -l: Current user's scheduled tasks
• sudo crontab -l: Root user's scheduled tasks

Quick System Overview Commands

# One-liner system summary
uname -a && uptime && free -h && df -h

# Hardware overview
lscpu && free -h && lsblk

# Network quick check
ip addr show && ss -tuln

# Process overview
ps aux --sort=-%cpu | head -10

Tips for Usage

• Use --help or man command_name for detailed options
• Many commands support -h for human-readable output
• Root privileges may be required for some hardware information commands
• Consider installing additional tools like htop, iotop, inxi for enhanced functionality
• Combine commands with pipes for filtered output: ps aux | grep process_name