ubuntu / Linux command cheatsheet

ubuntu_commands.md

Background

I am primary Mac user (MacBook Pro), and a secondary Windows / Linux User. I have a pretty powerful Windows 10 gaming PC with Nvida Graphic card) which I have recently turned into a Dual-bootable machine (bootable between Windows 10 and Ubuntu 16.04 LTS). Given I am a pretty new Ubuntu user I very frequently have to look up commands to perform certain actions. this post aims to serve as my personal cheatsheet (for Ubuntu commands).

Machine Specs:

• (Rough) MacBook Pro Spec: El Capitan, i7 CPUs, 1TB HDD, 16 GB RAM, Intel Graphic.
• (Rough) Gaming PC Spec: Dell XPS 8700, i7 CPUs, 16 GB RAM, 2TB HDD, onboard Intel Graphic card plus with a physical Nvida GeForce GTX 750 Ti Graphic Card).

Handy Commands

Here are some commands that are slightly beyond basics, but ultra handy.

How do I find out the model of my graphics card?

lspci | grep VGA to see if my NVIDIA 750Ti is detected.

ls -dl [ac]* - lists out only the directories beginning with the letter a or c at the current path Stackoverflow

cd - - go back to the previous directory. (it's sort of like back one page in a browser.)

ls -lh - list files within the current directory. The h shows the size of file / folder in a human readable format (kilo- / mega / giga / etc bytes). append these: a: show hidden file, d show directory only.

find . -name doc | wc -l - within the current directory, recursively find all files beginning with the string 'doc', then count & display observations.

Package mananager related:

• apt-get is high level package manager. dpkg is low level package manager.
• sudo apt-cache search lynx - search the lynx package on APT.
• sudo apt-get install lynx - install the lynx package (along with dependencies)
• sudo apt-get remove lynx - remove the lynx package (and leave the dependencies alone). This is a safe option.
• sudo apt-get autoremove lynx - remove the lynx package AND remove the dependencies (if not used by other packages). This is cleaner (providing you trust the publisher) but might cause problems. Avoid this.
• sudo apt-get upgrade - update all installed packages.

yelp man:cat - brings up the man page for the cat function via a GUI.

Processes related

• ps, ps -ef, ps -eLf
• pstree | head -10 - ps in graphical form.
• top - realtime load avearges and processes

(press following keys while using top)

key	action
t	Display or hide summary information (rows 2 and 3)
m	Display or hide memory information (rows 4 and 5)
A	Sort the process list by top resource consumers
r	Renice (change the priority of) a specific processes
k	Kill a specific process
f	Enter the top configuration screen
o	Interactively select a new sort order in the process list

Scheudling related

• crontab -l to display cron jobs
• crontab -r to cancel cron jobs
• crontab mycrontab to load the cron job from a bash script mycrontab
• at

Networking related

• host linuxfoundation.org - gives you the ip address of a web address.
• nslookup linuxfoundation.org - shows you domain name info.
• cat /etc/hosts - shows you the machine-IP mapping info.
• cat /etc/resolv.conf - shows you the dynamically resolved IP of your network.
• Lab: Network Troubleshooting - step-by-step guide.

Scripting related

• If Else condition
• Linux condition testing bracket
• myLen1=${#string1} - Saves the length of string1 in the variable myLen1.
• TEMP=$(mktemp /tmp/tempfile.XXXXXXXX) - create a temporary file.
• TEMPDIR=$(mktemp -d /tmp/tempdir.XXXXXXXX) - create a temporary directory

printing related

• cups package handles printing.
• ls command relates to printing from terminal.