Commonly used Linux/Unix commands and programs one should be vaguely familiar with. Not an exhaustive list of all tools - just a list of the essentials.

cli.md

File/Directory Management

• touch
• ls
• ln
• cp
• mkdir
• mv
• rm
• rmdir
• which
• readlink

Viewing/Searching Files:

• cat
• tail -f
• less
• more
• watch
• diff
• grep
• find
• wc -l
• lsof

Permissions/User Account

• chmod
• chown
• useradd, userdel
• passwd
• /etc/passwd, /etc/shadow, /etc/group /etc/gshadow

Remote File Transfer

• ssh
• scp
• ftp/sftp
• rsync
• wget
• curl

File System Commands

• lsblk
• fdisk
• du
• df
• fsck
• mkfs
• mount, umount

String Manipulation

• sed
• awk
• tr

Git

• git
  • init pull push fetch commit branch checkout merge cherry-pick log status add rm diff ...
  • git diff <COMMIT HASH>^ <COMMIT HASH> allows you to view the changes of a specific git commit. Can also use git show <COMMIT HASH>.
  • git log --graph --decorate for a colorful visual git log.

Networking

• dig
• traceroute
• ip r ip a ip link ...
• ping
• netcat nc
• nslookup
• tcpdump
• iptables
  • ufw
  • firewalld

System and Processes

• service
• systemctl
• ps commonly used with -aux or just aux
• top

Misc. Commands

• Search for an installed package/library: ldconfig -p | grep <package/library> or whereis <package/library>
• mdadm for managing linux software RAID.
• sort
• uniq most commonly uniq -c
• tar -xzvf <name-of-archive.tar.gz> extract a .tar.gz archive.
• tar -czvf <name-of-archive.tar.gz> </path/to/directory-or-file> create a .tar.gz archive.
• lspci lscpu
• dmidecode
• lshal - Get lots of hardware information (including some dmi info) without needing root access.
• uname -r Print the Kernel Release. Can also do cat /etc/*release* to check Linux distro/version.
• xargs -I% -P <Threads> -n <Max Args> Allows you to run multiple commands in parallel.
• socat
• visudo - Edit the /etc/sudoers file.
• modprobe - Add or remove modules from the Linux kernel.
• dkms - Rebuild dynamic kernel modules.
• ipmitool Used to query ipmi data and controlling ipmi devices. ipmitool sdr dumps sensor data.
• tee
• tar
  • tar -cvf archivename.tar /path/to/directory - Create an .tar archive of a directory.
  • tar -xvf archivename.tar - Extract (unpack) the .tar archive.
  • Add the -z flag to both commands to compress (gzip) the archive.

Useful (Bash) Tricks

• Use | to pipe the results from one command into another (e.g. cat names.txt | sort)
  • This is paramount to the "Unix Philiosphy"
• Stream redirection
  • < - Overwrite standard input
  • << - Append standard input
  • > - Overwrite standard output
  • >> - Append standard output
• history - View bash history.
  • You can then type !<number> to enter that command from your bash history.
• Ctrl+R - Search through bash history. Begin typing a search query, and can press Ctrl+R again to view more matches.
• -- two dashes signifies the end of command options, and allows you to specify "-" options as regular arguments.
  • e.g. cat -- -z would print out the contents of a file named "-z" while cat -z would print an error.
• & Add an ampersand after a command to make it run in the background.