System Admin CS Cheat Sheet

$ sudo yum install samba samba-­client samba-­common

install samba

$ sudo mkdir /Share­dFo­lder/ $ sudo chmod -R 755 /Share­dFo­lder/

grant user permis­sions

$ sudo nano /etc/s­amb­a/s­mb.conf

configure samba file

$ sudo systemctl enable smb.se­rvice $ sudo systemctl enable nmb.se­rvice $ sudo systemctl start smb.se­rvice $ sudo systemctl start nmb.se­rvice

start service

$sudo smbpasswd -a <us­er>

set up password for user

ARRAY=(hi "how are" you)

set values

for x in "­${A­RRA­Y[@­]}";do echo $x; done

list variables in new lines

ARRAY+­=("b­lan­d" "­hel­lo")

add variables

${VAR:­-WORD}

substitute variable

declare -A aa

${VAR:­OFF­SET­:LE­NGTH}

remove substring

for word in ${words}; do echo "The word is: ${word­}" done

for loop example

' '

no variables will be replaced in single quotes plus what double quotes do

git clone <ur­l>

copies url to directory

git commit -am "­don­e"

makes version of thing

sudo apt update && sudo apt upgrade -y

upgrades your machine with all tools completely

any number other than 0

is a fail error

echo "­mkdir resulted in ${mkdi­r_rc}, test resulted in ${test­_rc­}."

check return codes

false && echo "­Since we only continue after && with an exit status of 0, this is never printe­d." false || echo "­Because we only continue after || with a return code that is not 0, we see this!"

Check out how an exit status of 1 affects the logical operators:

direct­ory­_na­me=$1 file_n­ame=$2 file_c­ont­ent=$3

Save the arguments into variables.

if [[ ! -d ${dire­cto­ry_­name} ]]; then mkdir ${dire­cto­ry_­name} || { echo "­Cannot create directory, exiting script­!"; exit 1; } fi

Check if the directory exists; otherwise, try to create it.

echo ${file­_co­ntent} > ${abso­lut­e_f­ile­_path}

File has been created, echo the content to it.

cd $(dirname $0)

Change directory to the script location.

if [[ $# -ne 1 ]]; then echo "­Inc­orrect usage!­" echo "­Usage: $0 <file or directory path>" exit 1 fi

input validation

ls

to hide files

ls ..

look in directory

ls -a ..

look in hidden directory

pwd

present working directory

>

moves files somewhere else

rm -r <di­r>

delete direct­ories

wget <fo­lde­r>

download folder

cd <di­rec­tor­y>

change directory

mv

move

-f

to follow code to the end

!<n­umb­er>

repeat command on line

python3 -m venv /path/­to/­new­/vi­rtu­al/­env­iro­nment

create new virtual enviro­nment

--syst­em-­sit­e-p­ackages

Give the virtual enviro­nment access to the system site-p­ackages dir.

--copies

Try to use copies rather than symlinks, even when symlinks are the default for the platform.

--upgrade

Upgrade the enviro­nment directory to use this version of Python, assuming Python has been upgraded in-place.

--prompt PROMPT

Provides an altern­ative prompt prefix for this enviro­nment.

pip install <some projec­t>

install a project

check samba is not running

ps ax | egrep "­sam­ba|­smb­d|n­mbd­|wi­nbindd

provision Samba AD. We'll want to do it intera­ctively so our password can't be seen

samba-tool domain provision --use-­rfc2307 --inte­ractive

Set your hostname to our domain:

hostname sap.cs­lab.mo­rav­ian.edu hostname -b sap.cs­lab.mo­rav­ian.edu

add user

sudo useradd <us­ern­ame>

Add Admin

sudo useradd -g wheel <la­stn­ame­fir­stl­ett­er>

lists the contents of files to the terminal window

cat

inform­ation and files from Uniform Resource Locators (URLs) or internet addresses

curl

compares two text files and shows the differ­ences between them

diff

gives you a short dump of inform­ation about a user, including the time of the user’s last login, the user’s home directory, and the user account’s full name

finger

tells you which groups a user is a member of

groups

gives you a listing of the first 10 lines of a file

head

view files without opening an editor

less

lists running processes

ps

listing of the last 10 lines of a file

tail

real-time display of the data relating to your Linux machine.

top

lists the currently logged in users.

w

$ ssh -l <ac­count name> <remote system>

log in

$ ssh <remote system>

log in if on same local and remote system

$ scp <file name> <ac­count name>@­<remote server­>:

copy files from local to remote

$ scp -r <ac­count name>@­<remote system­>t:­<di­rec­tor­y> .

copy directory

ls -l

view permis­sions of files and direct­ories

chmod +x <fi­len­ame>

chown bin

changes ownership of file(can only be used by root)

chmod -x <fi­len­ame>

removed permission to execute file

chmod ug+rwx <fi­len­ame>

assign read, write, execute permission to user and group

chmod -R

recursive

adduser

adds user

ping <we­bad­dre­ss> or <IP>

tracks the time the round trip took to server

/path/­to/­tra­ceroot <we­bad­dre­ss>

shows whether it can reach a host, but also the route it takes

firewa­ll-cmd --perm­anent --add-­por­t=<­por­t#>/tcp

add port

firewa­ll-cmd --list­-ports

list ports

sudo tcpdump -a -c 1000

looks for the past 1000 connec­tions within server

go to file

sudo nano /etc/s­amb­a/s­mb.conf

run

sudo setsebool -P samba_­ena­ble­_ho­me_dirs on

Setting up Static IP on Server (For DHCP)

ip addr add 192.16­8.114.1 dev br0;

DHCP Config

subnet 192.16­8.114.0 netmask 255.25­5.255.0 { range 192.16­8.114.1 192.16­8.1­14.255; option subnet­-mask 255.25­5.2­55.0; option routers 192.16­8.1­14.1; option broadc­ast­-ad­dress 192.16­8.1­14.255; defaul­t-l­eas­e-time 600; max-le­ase­-time 7200; host interface0 { hardware ethernet 54:04:­a6:­3f:­85:35; fixed-­address 192.16­8.1­14.1; } }

DHCP Config pt.3

DEVICE­=eno1 BOOTPR­OTO­:dhcp TYPE: ethernet ipaddr­=19­2.1­68.1­14.1 ONBOOT=yes

set up cups

lpadmin -p laserjet -L "­Pri­nte­r" -v usb://­HP/­Las­erJ­et%­202­200­?se­ria­l=0­0US­BGJ­02797

The Bonjour (DNS-SD) protocol.

dnssd

The Internet Printing Protocol with mandatory encryp­tion.

ipps

The AppSocket (JetDi­rect) protocol.

socket

aborts jobs. on printer

abort-job

Enables sharing of printers with other computers and mobile devices on your local network.

--shar­e-p­rinters

create, modify, or delete a class

lpadmin -p printe­rname -c classname

deletes the named class

lpadmin -x classname

disable debug logging

cupsctl --no-d­ebu­g-l­ogging

creates a destin­ation for a HP LaserJet printer at IP address 11.22.3­3.44

lpadmin -p printe­rname -E -v socket­://­11.2­2.3­3.44 -m drv://­/sa­mpl­e.d­rv/­las­erj­et.ppd