CLI Commands and Cheat Sheet

Linux Command Line Interface Cheat Sheet. Main source.
Source for Curl command.

Basic

* # wildcard
? # represents

cd # go to home directory
cd .. # go up one level
cd /etc # go to /etc

ls # list files and subfolders
ls -l # with details
ls -a # display hidden files/folders
ls X # list the files

cmp A B # compare two files A and B, no output if identical
diff A B # compare two files A and B, outputs difference
pwd # display current path working directory
mkdir Y # create new Y folder
mv A B # move file in location A to location B

cp A B # move file in location A to location B
cp -r Y Z # recursively copy directory Y and its contents to directory Z

rm X # delete X permanently
rm -r Y # recursively remove directory Y
rm -f X # forcibly remove file X
rm -rf Y # forcibly remove directory Y
rmdir Y # remove directory, only if empty

open X # open X in default app
open -e-X # open X in default text editor
touch X # create empty file X

cat X # view contents of X
cat -b X # also display line numbers
wc X # display word count of X

head X # display the first 10 lines of X
head -n 4 X # show the first 4 lines of X
ls *.c | head -n 5 # display first 5 items of a list of *.c files

tail X # display last 10 lines of X
tail -n +1 X # display entire contents of X, with headers and file names
tail -f X # display the last 10 lines of X
less # read a file with foward and backwards navigation
cat file.txt | less # pipe file.txt and read it with fwd and bwd navigation

ln -s A S # create symbolic path A to link name S

Input/Output Redirection

echo TEXT # display line of TEXT or contents of a variable
echo -e TEXT # also interprets escape characters in TEXT (e.g. \n new line, \b backlash, \t tab)
cmd1 | cmd2 # | is the pipe character, feeds output of cmd1 to cmd2 (e.g. ps aux | grep python3)
cmd > file # redirect output of cmd to file
cmd >& file # redirect output of cmd to file, overwrites pre-existing content
cmd > /dev/ null # suppress the output of cmd
cmd >> file # append output of cmd into file
cmd < file # read input cmd from file
cmd <<< string # input text string to cmd
cmd 2> foo # redirect error messages of cmd to foo
cmd 2>> foo # append error messages of cmd to foo
cmd &> file # redirect output and errors messages of cmd to file

Search and Filter

grep patt /path/to/src # search for a text pattern patt in X (e.g. ps aux | grep python3)
grep -r patt /path/to/src # search recursively for text pattern patt
grep -v patt X # return lines in X not matching specified patt
grep -l patt X # write to standard output the names of files containing patt
grep -i patt X # perform case-sensitive matching on X, ignore case of patt

find # find files
find /path/to/src -name "*.sh" # ind all files in /path/to/src matching patter "*.sh" in filename
find /home -size +100M # find all files in the /home directory larger than 100MB

locate name # find files and directories by name
sort X # arrange lines of text in X alphabetically or numerically

File Transfer

ssh user@access # connect to access as user
ssh access # connect to access as local username
ssh -p port user@access # connect access as user using port

scp [user1@]host1:[path1] [user2@]host2:[path2] # login to hostN as userN for N=1,2
# (e.g. scp alice@pi:/home/source bob@arduino:/destination)
scp -P port [user1@]host1:[path1] [user2@]host2:[path2] # connect hostN as userN using port for N=1,2
scp -r [user1@]host1:[path1] [user2@]host2:[path2] # recursively cp all files/folders path1 to path2

sftp [user@]access # loging to access as user via SSH, no user means use local user
sftp access # connect access as your local username
sftp -P port user@access # connect to access as user using port

rsync -a [path1] [path2] # synchronize [path1] to [path2], preserves symbolic links, attr, etc.
rsync -avz host1:[path1] [path2] # synchronize [path1] on remote host1, to local [path2]

File Permissions

chmod permission file # change file/folder permissions (can be [u/g/o/a][+/-/=][r/w/x])
chown user2 file # change owner of file to user2
chgrp group2 file # change group of file to group2

chmod +x testfile # allow all users to execute the file
chmod u-w testfile # forbid current user from writing/changing file
chmod u+wx,g-x,o=rx testfile # simultaneously add write and execute permissions to user
# remove execute permission from gourp, and set permissions of other uses to only read and write

Octal	Permission(s)	Equivalent
0	No permissions	-rwx
1	Execute only	=x
2	Write only	=w
3	Write and Execute (2+1=3)	=wx
4	Read only	=r
5	Read and Execute (4+1=5)	=rx
6	Read and Write (4+2=6)	=rw
7	All permissions (4+2+1=7)	=rwx

chmod 777 testfile # all all users to execute file
chmod 177 testfile # execute-only to user (u); group (g) and others (o), read and executy only.
chmod 365 testfile # user (u) write+execute-only; group (g) read+write-only; others (o) r+exe only

Curl Commands

# Wttr.in
curl https://wttr.in/MSP?format=%l+%C+%h+%w+%t+feels+like+%f

# IP Cow
curl ip.wtf/moo

# Find and Listen
# Find everyone on the network, then start spoofing each MAC until you find a valid one.
nmap -sn 192.168.0.1-255

System Information

uname # show system info
uname -a # detailed system info
uname -r # kernel release info (version too)
uptime # how long the system is running
sudo # superuser
cal # show calendar with today highlighted
date # show current date and time of machine
halt # stop system immediately
shutdown # shut down the system
reboot # restart the system
last reboot # show reboot history
man <command> # show manual for given <command>
hostname # show system host name
hostname -I # display IP address of hort
cat /etc/*-release # current version of distro installer

Disk Usage

df # display free disk space
du # show file/folder sizes on disk
du -ah # disk usage in human readable format (e.g. KB, MB, etc)
du -sh # total disk usage of current directory
du -h # free and used space on mounted filesystems
du -i # free and used inodes on mounted filesystems
fdisk -l # list disk partitions, sizes, and types
free -h # display free and used memory in human readable units
free -m # display free and used memory in MB
free -g # display free and used memory in GB

Process Management and Performance Monitoring

& # add this character to run command/process in the background

ps # show process status (e.g. ps aux | grep python3)(all user, show user column, show unattached)
ps -e # print all running processes
ps -ef # print detailed overview
ps -U root -u root # display all processes running under root
ps -eo pid,user,command # display only columns pid, user, command in ps output

top # display sorted info about processes
htop # display sort info abotu processes with visual highlights
atop # display the detialed info about processes and hardware

kill PID # kill process with process ID PID
killall proc1 # kills all processes containing proc1 in their names

lsof # list all open files
lsof -u root # list all files opened by root (e.g. lsof -u root | less)

mpstat 2 # processor statistics updated every 2 seconds
vmstat 1 # virtual memory statistics updated 1 second
iostat 3 # system input/output statistics updated every 3 seconds

tail -n 100 /var/log/messages # display last 100 lines in system logs

tcpdump -i eth0 # capture and display all packets on interface eth0
tcpdump -i eth0 port 80 # monitor all traffic on interface eth0 port 80

watch df -h # execute df -h and show periodic updates (Ctrl + C to exit)

User Management

who # who is logged in
w # display what users are online and what doing
users # list current users
whoami # display what user you are logged in as
id # display the use ID and group ID for current user
last # display the last users who have logged onto the system
groupadd gp1 # create group name gp1
useradd -c "Alice Bob" -m ab1 # create account ab1 with comment "Alice Bob" and create new /home
userdel ab1 # delete account name ab1
usermod -aG gp1 ab1 # add the account ab1 to the group gp1

Networking

ifconfig # display network interfaces with IP addresses
ifconfig -a # display all network interfaces, eve if down, with IP addresses
ifconfig eth0 # display IP address abd details of the eth0 interface
ip a # another way to display all network interfaces with IP addresses
ethtools eth0 # query or control network driver and hardware settings on interface eth0

netstat # print open sockets, routing tables, inteace statistics, masq connections
netstat -a # show both listening and non-listening sockets (e.g. netstat -a | less)
netstat -l # show only listening sockets
netstat -nulp # show listening TCP and UDP ports and corresponding programs

ping host # ping host, may be symbolic name, domain name or IP address
whois domain # display whois info for domain
dig domain # display DNS info for domain
dig -x addr # rever lookup on IP addrress addr
host domain # display DNS IP address for domain
wget LINK # download from location LINK
curl LINK # display HTML source of LINK

Add a Bell at the End of a Script

; tput bel added to end of scripts to make a beep after it has complete source

Adding ”; tput bel” at the end of a script in Unix-like systems will cause the terminal to emit an audible bell sound when the script finishes executing. This is achieved by using the tput command, which is used to query and set terminal capabilities, and in this case, bel is one of those capabilities, representing the audible bell.

The semicolon (;) is a command separator in shell scripting, allowing multiple commands to be executed sequentially on a single line. So, when you add ”; tput bel” at the end of a script, it ensures that the bell sound is triggered after the script completes its execution, providing an audible signal to the user that the script has finished running.