Linux Basics Flashcards
cp
cp: Copy file
Copies file and keeps both copies
mkdir
mkdir: Make directory
Creates a new directory
Directories in Linux are the same as folders in Windows
vim
Used to edit any text based file in terminal
rm
rm: Remove
Deletes a file
mv
mv: Move file
Moves a file into another directory or subdirectory
rm -r
rm -r: Remove recursively
Delete an entire directory and all of its contents
touch
Creates a blank file; can be used to verify write permissions in a directory or to work around error messages showing a file is missing
df
df: Disk file system
Displays a full summary of the available and used disk space usage of a file system
-h
-h: Human readable
Since this starts with a - this is called a flag or modifier, it cannot be run on it’s own
Shows data sizes in KB/MB/GB, etc. instead of in Bytes
head
Shows the first 10 lines of a file
tail
Shows the last 10 lines of a file
tar
Compresses file; like Zip for Windows
Linux also can use zip/unzip for files
wget
wget: Website file get
Download a file from the web
top
Task Manager for terminal; same as Task Manager in Windows
k (Used within top)
Kill process by PID
PID
Process ID used in top
q
Quit
history
Shows the complete history of all commands ran on a machine
Each command is associated with a number; you can rerun any command by entering ! and the associated # (!23)
echo
Add text to the end of a file
Adds any data to the end of the desired file before the»_space;
echo Schedule an interview»_space; Prospective_ASRE_Candidates.txt
Prospective ASRE Candidates
Jane Doe
John Smith
Melodi Mullins Schedule an interview
echo
echo Cohesity > Employer.txt
Overwrites the data in a file to be replaced with whatever is typed before the >
In the example on the front, we can assume your Employer.txt file shows World’s Best Mama in the body and it will then be changed to Cohesity
sudo
sudo: Superuser do
Make the command run with admin credentials
cd
cd: Change directory
There are times that you will need to access different commands in different locations, this allows you to switch between locations and work as needed
ssh
Provides a secure encrypted connection between two hosts over an insecure network
You will use this command to connect to a node within a customer’s cluster
ssh 10.178.59.26
file
Displays file types
cat
Output (display) the contents of a text file
vi
Unix based text editor, similar to vim
netstat
netstat: Network status
Displays TCP connections, routing tables, and statistics
chmod
chmod: Change/modify
Change access permissions of file system objects
ls -a
ls: List
- a: Show all
List all including hidden files
pwd
pwd: Print working directory
Show (print) current directory name
flag
Flags are used to modify a command
cat hugefile.log | tail (tail is the flag)
Displays the last 10 lines of hugefile.log
cat hugefile.log | tail -n 5 (tail, -n, and 5 are each individual flags)
The tail command is modified to only display the last 5 lines of hugefile.log instead of the default 10
grep
Search a file for a particular pattern of characters, and displays all lines that contain that pattern
terminal
Any UI (User Interface) that allows you to enter commands
Common terminals are Ubuntu, WSL (Windows Subsystem for Linux), Terminal (Mac), RHEL (Redhat Enterprise Linux), MobaX
pipe
pipe: | (this looks like a l, but it is the capitalize character on the \ key
This is used to add additional commands to a command
cat error_logs.txt | grep power
cat displays error_logs.txt; since this will be a huge file and we know that we want to search for anything related to power so we add a pipe and tell it so search for the word power using grep
tfc
When tfc is used it allows you to connect directly to a customer’s cluster via terminal as well as opens the GUI (web based interface that customer’s use to manage their Cohesity software)
tfs
When tfs is used it allows you to connect directly to a customer’s cluster via terminal. It will only connect via terminal and opens nothing else.
tfb
When tfb is used it allows you to connect directly to a customer’s cluster via the GUI (web based interface that customer’s use to manage their Cohesity software), it will not connect via terminal
bang
bang: !
hostips
Lists all IP addresses within a cluster; the last one shown is the node you are connected to
Node
An individual component within a cluster, each node has it’s own IP address. There can be almost unlimited nodes within a cluster (the most I’ve run across is 80 within a cluster).
Cluster
A computer cluster is a set of computers that work together so that they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software.
