linux.md

Linux

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Learn Linux - Tutorials and Guides

Name	Comments
Linux Journey	Written guides + exercises + quiz
Techmint Linux	Written articles/lessons
Linux Survival	Interactive guide
NixCraft	Succinct guides
Linux Filesystem Explained	NSIA
Linux SysOps Handbook	A study notes book for the common knowledge and tasks of a Linux system admin.
LinuxToday	Contributor-driven news resources

Linux Internals - Articles

Name	Comments
How are Unix pipes implemented?

Linux Internals - Videos

Name	Comments
Understanding fork() system call for new process creation

Learn Linux - Videos

Name	Comments
learnlinux.tv	Very practical videos on various topics

Books

Author	Title	Comments
William Shotts	The Linux Command Line	Free
Christopher Negus	Linux Bible

Sites

Name	Comments
Linux From Scratch
Operating Systems: Three Easy Pieces

Videos

Presenter	Video	Length	Level
Joseph Delgadillo	The Complete Linux Course: Beginner to Power User!	07:23:52	Beginner

Tweak OS

Fedora disable alert sound

dconf write /org/gnome/desktop/sound/event-sounds "false"

Presentations

Author	Presentation	Level	Comments
Arie Bregman	Linux Networking	Beginner
Andrew McNico	tcpdump	Beginner

Cheat Sheet

Common Operations

• Copy files to a remote host: rsync -azv dir USER:REMOTE_HOST_ADDR
• View file size: du -sh DIR/FILE

Users

• Who is connected: w

Troubleshooting and Debugging

• see list of processes and the CPU and memory the consume: top
• show how long the server is up running: uptime
• List open files: lsof
• List open connections: lsof -i

SElinux

Get SElinux denials

semodule -DB

sudo ausearch -m avc -m user_avc -m selinux_err -m user_selinux_err -i -ts today

Communication

• Broadcast a message to everyone: wall

Tmux

• Join a session tmux a
• Attach to existing session: tmux attach -t <SESSION_NAME>
• New tab: ctrl + B + c
• New session called "bla": tmux new -s bla

Virsh

• Destroy: virsh destroy <vm_name>
• Shutdown: virsh shutdown <vm_name>

Date

• year: date +”%Y”
• month: date +”%m”
• day: date +”%a”

Fedora

• Reset "interface text" value: gsettings reset org.gnome.desktop.interface font-name
• Reset "monospace text" value: gsettings reset org.gnome.desktop.interface monospace-font-name
• Reset "document text" value: gsettings reset org.gnome.desktop.interface document-font-name
• Reset "Legacy Window Titles": gsettings reset org.gnome.desktop.wm.preferences titlebar-font

Files

• Sort files by size: ls -l | sort -nk5
• Find broken links: find /some/path -type l -exec test ! -e {} \; -print

LDAP

• LDAP search for a username: ldapsearch -x -W -D username
• LDAP search for a username specifying DC and ldap server: ldapsearch -x -H ldap://ldap.blabla.com -LLL -b 'dc=DOMAIN,dc=com' "rhatNickName=abregman"

YAML

• Validate YAML file with Ruby: ruby -ryaml -e "p YAML.load(STDIN.read)" < some_file.yaml
• Validate YAML file with Python: pip install pyyaml; python -c 'import yaml, sys; print(yaml.safe_load(sys.stdin))' < some_file.yaml

Misc

• Random string of 7 characters: mkpasswd -l 8
• Generate 8 digit random number: shuf -i 9999999-99999999 -n 1

Checklist

Check your Linux educational progress with the following list:

• File System Hierarchy

  • / (aka root)

  • /bin and /sbin

  • /opt

  • /usr

  • /var

  • /home

  • /etc

  • /proc

  • /tmp

  • Test

    • What is '/'?
    • What is stored in '/bin'? what about /etc?
    • What '/home' is usually used for?
    • What type of files can you find in '/var'?
    • What is unique about /tmp?

• Navigation

  • Commands

    • pwd - where am I?
    • cd - change directory

  • relative vs. absolute paths

  • Test

    • How to check your current path?
    • Where cd .. will take you?
    • What would be the effect of running cd .?
    • What will happen when running 'cd -'?

• Files

  • Types of files

    • Regular
    • Directory
    • Socket
    • Block
    • Link

  • Commands

    • ls - list files and directories
      • -a for listing hidden files
      • -l for list formt
      • -t order by time
      • -F better distinguish between regular files and directories
    • touch - creating files (original intention is updating timestamp)
      • nice to know: touch file{1..5}
    • rm - remove files
      • -r for recursive
      • -f to force removal, no questions asked
    • mkdir - create directories
      • -p - for creating multiple nested directories
    • rmdir - remove directories
    • echo - display a line of text
    • cat - concatenate files (common usage: read a file)
    • mv - move files directories (also rename files and directories)
    • cp - copy a file
      • -r for recursive (copy a directory)

  • Test

    • How to list hidden files?
    • How to create an empty new file?
    • How to remove a directory?
    • How to rename a file?
    • How to copy an entire directory with all its files?

• Commands

  • man - manual for commands
  • which - get full path for given command
  • whatis - one-line manual page descriptions

• I/O redirection

  • File Descriptor

    • stdin 0 (input) <
    • stdout 1 (output) >
    • stderr 2 (error) 2>

  • Append >>

  • Test

    • How to redirect output?
    • What would be the result of the following command blop 2> file?

• Text Editor (one is enough)

  • vim

    • i to start typing
    • :wq to exit (or shit+zz)

  • nano

  • emacs

  • atom

  • sublime

  • Test (mainly for vim)

    • How to remove an entire line?
    • How to copy 5 lines?
    • How to jump to the end of the line
    • How to remove one word
    • How to jump to the end of the file

• Users

  • Commands

    • useradd
    • usermod
    • userdel
    • who

  • Nice to know commands

    • lastlog

  • Test

    • how to add a new user?
    • should you be using your user or root?

• Network

  • netstat

• Monitoring and performence commands

  • top
  • stat

• Processes

  • Running in ackground (&)

• Archives

  • what is it good for
  • tar
  • zip
  • commands
    • create an archive
    • list archive's content
    • remove an archive

• Storage, Filesystem

  • inode