HON95-wiki/config/general/linux-examples.md

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title: Linux Examples breadcrumbs:

• title: Configuration
• title: General --- {% include header.md %}

Commands

File Systems and Logical Volume Managers

• Partition disk: gdisk <dev> or fdisk <dev>
• Create filesystem: mkfs.<fs> <dev>
• Modify fstab:
  • Test it with mount -a to make sure it doesn't have errors that may cause boot to fail.
  • Run systemctl daemon-reload to avoid having systemd remount stuff that was removed from fstab or other weird shit.

Files

• Search:
  • By UID: find / -user <UID>
  • Without a user: find / -nouser
  • With setuid permission bit: find / -perm /4000
  • Recursive search and replace: find <dir> \( -type d -name .git -prune \) -o -type f -print0 | xargs -0 sed -i 's/123/456/g'
    • -type d -name .git -prune skips .git directories and can be excluded outside of git repos.
• Usage:
  • du -sh <dirs>
  • K4DirStat (GUI) (package k4dirstat)
• Shred files:
  • shred --remove --zero <file>

Fun

• Color text from STDIN: lolcat
• cowsay
• fortune

Hardware

• Show hardware: lshw
  • Run as root for more info.
  • Specify -X to show GUI (requires lshw-gtk).
• Show hardware topology: lstopo (requires hwloc)
  • lstopo will try to present as a GUI. Use lstopo-no-graphics to force console output.
• Show PCI devices: lspci
• Show block devices: lsblk
• Show USB devices: lsusb
• Show CPUs: lscpu

Installations and Packages

APT (Debian)

• Find packages depending on the package: apt rdepends --installed <package>
• Quickly add new repo: add-apt-repository <repo-line
  • It will add the line to /etc/apt/sources.list, where you can manually remove it again.
• Keys:
  • List: apt-key list
    • It will also show which file contains it.
  • Remvoe key: apt-key del <key-id>
    • The 8-digit hex key ID may either be found on pub line or as the last 8 hex digits on the continuation line.

Network

• Monitor usage:
  • nload <if>
  • iftop -i <if>
  • speedometer -t <if> -r <if> [...]
• Monitor per-process usage:
  • nethog
• Test throughput:
  • Internet: speedtest (the official one, not speedtest-cli)
  • Internal: iperf3
• Show sockets:
  • netstat -tulpn
    • tu for TCP and UDP, l for listening, p for protocol, n for numerical post numbers.
  • ss <options>
• Show interface stats:
  • ip -s link
  • netstat -i
• Show interfaces and addresses:
  • IPv4 and/or IPv6 plus MAC: ip [-46] a
  • Only global IPv4/IPv6: ip <-46> a show scope global
• Show neighbors:
  • ip n
• Show routes:
  • ip r & ip -6 r
  • netstat -r
• Show multicast groups:
  • netstat -g
• Show misc. stats:
  • nstat
  • netstat -s (statistics)

Performance and Power Efficiency

• Set the CPU frequency scaling governor mode:
  • High performance: echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
  • Power save: echo powersave | ...
• Show current core frequencies: grep "cpu MHz" /proc/cpuinfo | cut -d' ' -f3

Security

• Show CPU vulnerabilities: tail -n +1 /sys/devices/system/cpu/vulnerabilities/*

Storage

• Test read speed: hdparm -t <dev> (safe)
• Show IO load for devices: iostat [-dxpm] [-t] [interval]
  • -d: Show only device usage.
  • -x and -p: Include extended attributes and partitions.
  • -t and interval: Show timestamp and repeat every x seconds.
• Show IO usage for processes: iotop -o [-a]

System

• Version info:
  • Release info files:
    • Debian (and Ubuntu): /etc/debian_version
    • RHEL: /etc/redhat-release
    • CentOS: /etc/centos-release
  • General release info: uname -a
  • Slightly more distro-specific release info: lsb_release -a
• Monitor system load:
  • uptime
  • iostat [-c] [-t] [interval]
• Monitor processes:
  • ps (e.g. ps aux or ps ax o uid,user:12,pid,comm)
• Monitor a mix of things:
  • htop
  • glances
  • ytop
• Monitor interrupts:
  • irqtop
  • watch -n0.1 /proc/interrupts
• Stress test:
  • Stress CPU: stress-ng -c $(nproc) -t 600

Tasks

Burn Windows ISO

1. Install the graphical application woeusb from ppa:nilarimogard/webupd8.

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