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@dcchambers
Last active Apr 23, 2020
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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.

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)
  • 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.
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