Update tech_docs/linux/linux_show.md

tech_docs/linux/linux_show.md

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 - **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.
 
+---
+
+# 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
+```bash
+# 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`