Linux Comprehensive

gistfile1.txt

System Monitoring

    top: Real-time process and resource usage.
        Example: top
    htop: Interactive process viewer.
        Example: htop
    vmstat: System performance (CPU, memory, I/O).
        Example: vmstat 5 10
    iostat: Disk I/O and CPU usage stats.
        Example: iostat -x 1
    uptime: System uptime and load averages.
        Example: uptime
    free: Memory usage.
        Example: free -h
    dmesg: Kernel and boot logs.
        Example: dmesg | tail
    sar: System activity reporter.
        Example: sar -u 1 5
    lsof: List open files.
        Example: lsof -i :80 (Processes using port 80)
    watch: Run a command periodically.
        Example: watch df -h

File and Directory Management

    ls: List files.
        Example: ls -lah
    cp: Copy files.
        Example: cp file1 file2
    mv: Move or rename files.
        Example: mv oldname newname
    rm: Delete files or directories.
        Example: rm -rf /tmp/test
    find: Search for files.
        Example: find /var -name "*.log"
    locate: Find files quickly.
        Example: locate apache.conf
    du: Disk usage of files/directories.
        Example: du -sh /var/log
    df: Disk space usage of filesystems.
        Example: df -h
    stat: Display detailed file info.
        Example: stat myfile
    file: Identify file type.
        Example: file /bin/bash
    touch: Create an empty file.
        Example: touch newfile
    chmod: Change permissions.
        Example: chmod 755 script.sh
    chown: Change ownership.
        Example: chown user:group file
    ln: Create links.
        Example: ln -s /path/to/file shortcut

Networking

    ip: Manage IP addresses, routes, and devices.
        Example: ip addr show
    traceroute: Trace the route to a host.
        Example: traceroute google.com
    ping: Test connectivity.
        Example: ping -c 4 8.8.8.8
    netstat: Network connections and stats (deprecated, use ss).
        Example: netstat -tuln
    ss: Modern replacement for netstat.
        Example: ss -tuln
    curl: Transfer data from/to a URL.
        Example: curl -I https://example.com
    wget: Download files.
        Example: wget https://example.com/file.zip
    tcpdump: Capture network packets.
        Example: tcpdump -i eth0 port 80
    dig: Query DNS information.
        Example: dig example.com
    nslookup: DNS lookup.
        Example: nslookup example.com
    nmap: Network scanner.
        Example: nmap -p 80 example.com
    arp: View ARP table.
        Example: arp -a
    iptables: Manage firewall rules.
        Example: iptables -L -v -n
    ethtool: View and modify NIC settings.
        Example: ethtool eth0

Process Management

    ps: List running processes.
        Example: ps aux | grep nginx
    kill: Terminate processes by PID.
        Example: kill -9 12345
    pkill: Terminate processes by name.
        Example: pkill nginx
    jobs: List background jobs.
        Example: jobs
    fg: Bring a background job to the foreground.
        Example: fg %1
    bg: Resume a job in the background.
        Example: bg %1
    strace: Trace system calls and signals.
        Example: strace -p 12345
    nice: Start a process with a custom priority.
        Example: nice -n 10 ./script.sh
    renice: Change priority of a running process.
        Example: renice -n 5 -p 12345

System Administration

    whoami: Display current username.
        Example: whoami
    id: Display user ID and group info.
        Example: id username
    hostname: Display or set hostname.
        Example: hostname
    uptime: Show uptime and load average.
        Example: uptime
    uname: Show system info.
        Example: uname -a
    lsb_release: Show Linux distribution info.
        Example: lsb_release -a
    shutdown: Shutdown or restart system.
        Example: shutdown -h now (Shutdown immediately)
    reboot: Reboot system.
        Example: reboot

Disk and Filesystem Management

    mount: Mount a filesystem.
        Example: mount /dev/sda1 /mnt
    umount: Unmount a filesystem.
        Example: umount /mnt
    fsck: Check and repair filesystems.
        Example: fsck /dev/sda1
    mkfs: Create a filesystem on a device.
        Example: mkfs.ext4 /dev/sdb1
    blkid: Display block device info.
        Example: blkid
    lsblk: List block devices.
        Example: lsblk
    tune2fs: Adjust filesystem parameters.
        Example: tune2fs -l /dev/sda1

Security

    passwd: Change user password.
        Example: passwd
    ssh: Connect to a remote server via SSH.
        Example: ssh user@hostname
    scp: Copy files over SSH.
        Example: scp file user@hostname:/path/to/dest
    rsync: Synchronize files/directories.
        Example: rsync -avz /src /dest
    chmod: Change file permissions.
        Example: chmod 755 script.sh
    chown: Change file ownership.
        Example: chown user:group file
    gpg: Encrypt and decrypt files.
        Example: gpg -c file.txt

Compression and Archiving

    tar: Create and extract archives.
        Example: tar -czvf archive.tar.gz /path/to/files
    zip: Compress files into a zip archive.
        Example: zip archive.zip file1 file2
    unzip: Extract files from a zip archive.
        Example: unzip archive.zip
    gzip: Compress files using gzip.
        Example: gzip file
    gunzip: Decompress gzip files.
        Example: gunzip file.gz