Linux Checklist for Beginners

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
  • [ ] Character Device
  • [ ] Block Device
  • [ ] Link
  • [ ] Named Pipe

• [ ] 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
  • [ ] 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)
  • [ ] less - display files on a page-by-page basis

• [ ] 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?

Pattern Matching

This also known as File Globbing

• [ ] Patterns
  • [ ] * - matches zero or more of any character
  • [ ] ? - matches one of any character

Commands

• [ ] man - manual for commands
• [ ] which - get full path for given command
• [ ] whatis - one-line manual page descriptions
• [ ] history - command history list
  • [ ] use ![number line] to execute a command from the list

Random

• [ ] Terminal

  • [ ] clear - clear the terminal screen (ctrl+l can be also used)
  • [ ] ctrl+r- history search of commands
  • [ ] exit (or logout) - terminate a process, quit the shell

• [ ] Commands

  • [ ] echo - display a line of text
  • [ ] alias - define or display command shortcuts/aliases
  • [ ] wc - count lines, words, ...

• [ ] Distributions

  • [ ] Fedora
  • [ ] Ubuntu
  • [ ] RHEL, CentOS
  • [ ] Mint
  • [ ] Debian
  • [ ] Arch Linux
  • [ ] openSUSE

I/O redirection

• [ ] File Descriptor
  • [ ] stdin 0 (standard input) <
  • [ ] stdout 1 (standard output) >
  • [ ] stderr 2 (standard error) 2>

• [ ] Append >>

• [ ] Pipe

  • [ ] For example: cat file | wc -l to count number of lines

• [ ] tee

  • [ ] Writing output to two different streams
  • [ ] Test

• [ ] How to redirect output?

• [ ] What would be the result of the following command blop 2> file?

Text Editor

Learning how to use one of them is more than 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

• [ ] Types of users

  • [ ] regular
  • [ ] root

• [ ] Commands

  • [ ] useradd - add users
  • [ ] usermod - modify users
  • [ ] userdel - delete users
  • [ ] who - show who is logged on
  • [ ] lastlog - recent login of users

• [ ] Files

  • [ ] /etc/passwd - stores users information
  • [ ] /etc/shadow - passwords

• [ ] Test

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

Network

• [ ] Commands

  • [ ] ping - test the reachability of a host
  • [ ] -c for number of packets
  • [ ] ip - manage routing, network devices, interfaces and tunnels
  • [ ] ip a for interfaces
  • [ ] ip r for routing
  • [ ] ip neigh for any ARP related operation
  • [ ] ethtool - query and manipulate driver and hardware settings
  • [ ] -p for interface led blinking
  • [ ] -t for running tests to check your network interface
  • [ ] -S for getting statistics
  • [ ] arp- manipulate the system ARP cache
  • [ ] dhclient- DHCP client
  • [ ] netstat - display network connections
  • [ ] -n for IP addresses instead of hostnames
  • [ ] -t to show only TCP connections
  • [ ] -p to show the PID of the program
  • [ ] -l to show only listening sockets
  • [ ] lsof - list open files
  • [ ] -i for sockets
  • [ ] traceroute - print the route packets trace to network host
  • [ ] mtr - network diagnostic tool (traceroute + ping)

• [ ] Files

  • [ ] /proc/net/dev - network interfaces list
  • [ ] /pro/net/arp - ARP table
  • [ ] /etc/sysconfig/network-scripts/* - network configuration files in RHEL based OSs
  • [ ] /etc/network/interfaces - network configuration files in Ubuntu

• [ ] Types of interfaces

  • [ ] Regular
  • [ ] Dummy
  • [ ] Virtual IP
  • [ ] Veth

• [ ] Bonding

  • [ ] Modes
  • [ ] How to activate

• [ ] Network Namespaces

  • [ ] ip netns
  • [ ] ip netns add for adding namespaces
  • [ ] ip netns list for listing namespaces
  • [ ] ip netns del for removing namespaces
  • [ ] ip netns exec for executing commands inside a network namespace

• [ ] Network Kernel Parameters

  • [ ] sysctl net.*
  • [ ] /proc/sys/net/*

• [ ] Packet Sniffers (one is enough)

  • [ ] tcpdump
  • [ ] wireshark
  • [ ] dhcpdump
  • [ ] httpry

• [ ] Test

  • [ ] How to list the interfaces in your system?
  • [ ] How to display the routing table?
  • [ ] How to change the MTU of an interface?

Debugging & Troubleshooting

• [ ] CPU and Memory

  • [ ] top - processes memory and cpu consumption
  • [ ] free - amount of free and used memory
  • [ ] -g for the amount of memory in gigabytes
  • [ ] vmstat - virtual memory statistics
  • [ ] htop - interactive process viewer
  • [ ] atop - system and process monitor
  • [ ] /proc/meminfo

• [ ] Network Commands

  • [ ] netstat - network connections
  • [ ] traceroute - network connections
  • [ ] IPTraf - IP LAN monitoring
  • [ ] iftop - network bandwidth monitoring

• [ ] Disk and Filesystem

  • [ ] iotop - I/O monitor
  • [ ] iostat - I/O statistics for devices and partitions

Processes

• [ ] States

  • [ ] Running
  • [ ] Waiting
  • [ ] Stopped
  • [ ] Zombie

• [ ] Files

  • [ ] /proc/[PID]

• [ ] Running in the background

  • [ ] For example: my_program &

Archives

• [ ] Commands

  • [ ] tar
  • [ ] gzip
  • [ ] zip
  • [ ] unzip

• [ ] Test

  • [ ] How to create an archive?
  • [ ] How to extract the content of an archive?

Files - Part 2

• [ ] Commands
  • [ ] find - search for files
  • [ ] sort - sort, merge, or sequence check text files
  • [ ] sort - sort, merge, or sequence check text files

Storage & Filesystem

• [ ] inode

• [ ] Links

  • [ ] soft link
  • [ ] hard link

• [ ] Commands

  • [ ] file - determine file type
  • [ ] stat - file or file system status

• [ ] LVM

  • [ ] pv
  • [ ] vg
  • [ ] lv

• [ ] Test

  • [ ] Can you create soft links between different file systems? what about hard links?
  • [ ] What information inode stores?

Hardware

• [ ] Commands
  • [ ] lshw - list hardware
  • [ ] lspci - list all PCI devices
  • [ ] dmidecode - DMI table decoder

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