3.0 Master Set

linux has super user account called

root

linux is

• case sensitive, file ABC is not the same as file abc

when creating files avoid using

spaces

linux kernel is

Not an operating system, it is a small software that takes commands from users and passes them to system hardware

2 types of access

console

• remote

command to remotely access linux machine

• ssh 192.168.1.1

command to remote into linux machine with username

• ssh -l <username> <ip-address>

get ip address

ip addr

command prompt order

username - hostname - prompt symbol

get prompt back

ctrl + c

get username

whoami

get hostname

hostname

there are 3 types of root on a linux system

• root account → has access to all commands

• / → root directory

• /root → root home directory

change password

passwd userid

linux file systems

ext3, ext4, xfs

go to a different directory

cd

directory where log files are located

/var

directory where commands are located

/sbin

directory that contains files used by bootloader

/boot

directory that contains root user home directory

/root

directory that contains configuration files

/etc

directory that contains system devices

/dev

directory that contains everyday user commands

/usr/bin

directory that contains system file commands

/usr/sbin

directory that contains optional add ons

/opt

directory that contains running processes used only in memory

/proc

directory that contains programming library files

/usr/lib

directory that contains temporary files

/tmp

directory that contains system logs

/var

switch directories

cd

find which directory you are currrently in

pwd

list the contents of a file

ls <filename>

c: drive (windows) is the same as what in linux

/

become root

su -

wipe the screen

clear

when doing ls… anything that starts with - is a

file

when doing ls… anything that starts with d is a

directory

go one directory back

cd ..

when doing ls… anything that starts with l is a

link

an absolute path always begins with

/

command to create a file

touch <filename>

copy an existing file

cp <filename> <new-file>

create a directory

mkdir

check that file/dir was created

ls -l

list files by when it was last modified

ls -ltr

ls -ltr sorts by

oldest at top, newest at bottom

create vi file

• vi <filename>

• :wq!

create multiple files

touch file1 file2 file3

copy a directory

cp -R <source> <destination>

two main commands used to search for files

• find

  • locate

use the find command to search for a file

find . -name “<name">”

if locate command doesn’t work

updatedb

use locate command to search for files

locate <filename>

difference between find . and find /

• . means current directory

• / means start the search from root

use find command to search from current directory

find . -name “<filename>”

use find command to search from root

find / -name “<name>”

which is faster locate or find

locate

to run updatedb you need to be

root or use sudo

*

represents anything

?

represents a single character

[ ]

represents a range of character

use a wildcard to remove EVERY file that starts with abc

rm abc*

remove a directory

rm -r <dir.name>

create 9 files using a wildcard

touch abcd{1..9}

remove everything that ends with xyz

rm *xyz

file symbol -

regular file

file symbol d

directory

file symbol l

link

file symbol c

special file or device file

file symbol s

socket

file symbol p

named pipe

file symbol b

blocked device

in windows a directory is called a

folder

2 types of links

soft links and hard links

if you attach a keyboard to your system the linux OS

creates a c file

socket files are used for

network communication between processes

named pipe files

FIFO (first in, first out)

inode

pointer or number on a file

soft link

link that when created will be removed if file is removed or renamed

how do links work

they point towards inode

hard link

deleting or renaming source file will not remove link

create a hardlink

ln <source> <destination>

create a soft link

ln -s <source> <dest>

write to a file

echo “<text”>

read what you wrote to the file

cat <filename>

find inode of file

ls -li <file>

linux has a super user called

root

linux is

case-sensitive

avoid using

spaces

is linux kernel an OS

FUCK NO

2 types of access

• console

• remote

remote access linux to linux

ssh 192.168.1.1

get your prompt back

ctrl + c

how to open terminal

right click desktop

Get the username

whoami

find the name of your machine

hostname

go to root directory

cd /

root home directory

/root

change a password

passwd userid