EEE120 Terminal Cheat Sheet 🖥️

pwd	Print Working Directory (shows where you are).
whoami	Shows your account username.
cd [dir]	Change Directory. Use cd .. to go up, cd to go home.
cd -	Go to the previous directory you were in.
ls	List files and directories.
ls -l	List with long format (permissions, owner, size).
ls -a	List all files (including hidden . files).
ls -alF	Combine flags: all, long, F (adds / to dirs).
history	Shows command history. history -75 shows last 75.
Up Arrow	Scroll through last-used commands.
Tab	Auto-completes filenames or commands.
clear	Clears the terminal screen.
man [cmd]	Shows the manual for a command (e.g., man ls).
which [cmd]	Shows the full path to a command (e.g., which ls).

mkdir [name]	Make a new directory.
touch [file]	Creates a new, empty file (or updates timestamp).
cp [src] [dest]	Copy a file. (e.g., cp hi.txt bye.txt).
cp -r [src] [dest]	Copy recursively (copies a whole directory).
mv [src] [dest]	Move a file or directory. Also used to rename files.
rm [file]	Remove a file. Be careful! This is permanent.
rmdir [dir]	Remove an empty directory.
rm -r [dir]	Remove a directory recursively (and all its contents).
ln [target] [link]	Creates a hard link between two files.
ln -s [target] [link]	Creates a symbolic link (a "shortcut"). More common.

echo "text"	Prints "text" to the terminal.
cat [file]	Concatenate. Dumps the entire file content to the screen.
cat f1.txt f2.txt	Combines and prints two files.
more [file]	View a file one page at a time (scroll down only).
less [file]	View a file one page at a time (scroll up and down). (more is less!)
head [file]	Shows the first 10 lines of a file.
tail [file]	Shows the last 10 lines of a file.
nano [file]	Opens the nano text editor to create or edit a file.

find . -name "f.txt"	Finds files with -name starting from . (current dir).
grep "term" [file]	Searches for "term" inside a file.
grep -r "term" .	Searches recursively for "term" in all files in current dir.
sort [file]	Sorts the lines of a file alphabetically.
| (Pipe)	Pipeline. Uses the output of one command as the input for another.
sort f.txt | grep "e"	Example: sorts the file, then pipes the sorted list to grep.
> (Redirect)	Redirects standard output to a file (overwrites).
ls > files.txt	Example: Puts the output of ls into files.txt.
>> (Append)	Redirects output to a file (appends to end).
< (Input)	Redirects standard input from a file.
./app < input.txt	Example: Runs app and feeds it input.txt as if you typed it.

ls -l shows permissions like -rwxr-xr--

• First char: d (directory) or - (file).
• Group 1: Owner (rwx = Read, Write, eXecute)
• Group 2: Group (r-x = Read, no Write, eXecute)
• Group 3: Other (r-- = Read, no Write, no eXecute)

chmod [###] [file]	Change mode (permissions) using numbers.
4=Read, 2=Write, 1=X	Permission numbers. Add them up for each group.
chmod 755 script.sh	Owner: 7 (4+2+1), Group: 5 (4+0+1), Other: 5 (4+0+1).
chmod 660 file.txt	Owner: 6 (4+2+0), Group: 6 (4+2+0), Other: 0.
sudo [command]	Super User Do. Runs a command as administrator.
sudo chown [user] [file]	Change owner of a file.
sudo chgrp [group] [file]	Change group of a file.

ping [ip/host]	Sends packets to a host (e.g., ping 8.8.8.8). (Ctrl+C to stop).
traceroute [host]	Traces the network hops to a host.
ifconfig	Shows network interface configuration (your IP address).
ps	Shows your active processes.
ps aux	Shows all processes from all users in detail.
top	Shows a dynamic, real-time list of processes. (q to quit).
[cmd] &	Runs a command in the background.
Ctrl+Z	Suspends the current foreground job.
jobs	Lists suspended or background jobs.
bg %1	Puts job %1 into the background.
fg %1	Brings job %1 to the foreground.
kill [PID]	Kills a process by its Process ID (get from ps).
kill -9 [PID]	Force-kills a stubborn process.

alias fs=./script.sh	Creates a shortcut fs to run your script.
unalias fs	Removes the fs alias.
tar -zcvf a.tar.gz [dir]	Tape Archive: zip, create, verbose, file. Compresses [dir].
tar -xzvf a.tar.gz	Extracts (unzips) the .tar.gz file.
ssh [user]@[host]	Secure Shell. Logs into a remote server.
scp [file] [user]@[host]:~	Secure Copy. Sends [file] to the remote host's home (~) dir.
logout	Logs out of an ssh session.

du -h	Disk Usage for current dir, in human-readable format.
df -h	Disk Free space for all volumes, in human-readable format.
brew install [name]	(Homebrew) Installs software. (e.g., brew install htop).
brew update	(Homebrew) Updates the list of available software.
brew upgrade	(Homebrew) Upgrades all installed software.

A file like firstScript.sh. Run with ./firstScript.sh after chmod 755.

#!/bin/bash
# ^ This is the "shebang", tells the OS to use bash

i=1
echo "Enter a number: "
read a # Read user input into variable 'a'

# Check if input is a positive integer
if ! [[ $a =~ ^[0-9]+$ ]] || (( a < 1 )); then
   echo "Error: please enter a positive integer." >&2
   exit 1
fi

while [[ $i -le $a ]]; do
   echo "$i"
   if (( i % 2 == 0 )); then
       echo "$i is divisible by 2"
   else
       echo "$i is odd"
   fi

   if (( i % 6 == 0 )); then
       echo "$i is divisible by 6"
   fi
   (( i += 1 )) # Increment 'i'
done

ls # Runs 'ls' at the end of the script

pwd	Print Working Directory (shows where you are).
whoami	Shows your account username.
cd [dir]	Change Directory. Use cd .. to go up, cd to go home.
cd -	Go to the previous directory you were in.
ls	List files and directories.
ls -l	List with long format (permissions, owner, size).
ls -a	List all files (including hidden . files).
ls -alF	Combine flags: all, long, F (adds / to dirs).
history	Shows command history. history -75 shows last 75.
Up Arrow	Scroll through last-used commands.
Tab	Auto-completes filenames or commands.
clear	Clears the terminal screen.
man [cmd]	Shows the manual for a command (e.g., man ls).
which [cmd]	Shows the full path to a command (e.g., which ls).

mkdir [name]	Make a new directory.
touch [file]	Creates a new, empty file (or updates timestamp).
cp [src] [dest]	Copy a file. (e.g., cp hi.txt bye.txt).
cp -r [src] [dest]	Copy recursively (copies a whole directory).
mv [src] [dest]	Move a file or directory. Also used to rename files.
rm [file]	Remove a file. Be careful! This is permanent.
rmdir [dir]	Remove an empty directory.
rm -r [dir]	Remove a directory recursively (and all its contents).
ln [target] [link]	Creates a hard link between two files.
ln -s [target] [link]	Creates a symbolic link (a "shortcut"). More common.

echo "text"	Prints "text" to the terminal.
cat [file]	Concatenate. Dumps the entire file content to the screen.
cat f1.txt f2.txt	Combines and prints two files.
more [file]	View a file one page at a time (scroll down only).
less [file]	View a file one page at a time (scroll up and down). (more is less!)
head [file]	Shows the first 10 lines of a file.
tail [file]	Shows the last 10 lines of a file.
nano [file]	Opens the nano text editor to create or edit a file.

find . -name "f.txt"	Finds files with -name starting from . (current dir).
grep "term" [file]	Searches for "term" inside a file.
grep -r "term" .	Searches recursively for "term" in all files in current dir.
sort [file]	Sorts the lines of a file alphabetically.
| (Pipe)	Pipeline. Uses the output of one command as the input for another.
sort f.txt | grep "e"	Example: sorts the file, then pipes the sorted list to grep.
> (Redirect)	Redirects standard output to a file (overwrites).
ls > files.txt	Example: Puts the output of ls into files.txt.
>> (Append)	Redirects output to a file (appends to end).
< (Input)	Redirects standard input from a file.
./app < input.txt	Example: Runs app and feeds it input.txt as if you typed it.

ls -l shows permissions like -rwxr-xr--

• First char: d (directory) or - (file).
• Group 1: Owner (rwx = Read, Write, eXecute)
• Group 2: Group (r-x = Read, no Write, eXecute)
• Group 3: Other (r-- = Read, no Write, no eXecute)

chmod [###] [file]	Change mode (permissions) using numbers.
4=Read, 2=Write, 1=X	Permission numbers. Add them up for each group.
chmod 755 script.sh	Owner: 7 (4+2+1), Group: 5 (4+0+1), Other: 5 (4+0+1).
chmod 660 file.txt	Owner: 6 (4+2+0), Group: 6 (4+2+0), Other: 0.
sudo [command]	Super User Do. Runs a command as administrator.
sudo chown [user] [file]	Change owner of a file.
sudo chgrp [group] [file]	Change group of a file.

ping [ip/host]	Sends packets to a host (e.g., ping 8.8.8.8). (Ctrl+C to stop).
traceroute [host]	Traces the network hops to a host.
ip addr	Shows network ip addresses (your IP address). (Modern)
ifconfig	(Older) Shows network interface configuration.
ps	Shows your active processes.
ps aux or ps -ef	Shows all processes from all users in detail.
top or htop	Shows a dynamic, real-time list of processes. (q to quit).
[cmd] &	Runs a command in the background.
Ctrl+Z	Suspends the current foreground job.
jobs	Lists suspended or background jobs.
bg %1	Puts job %1 into the background.
fg %1	Brings job %1 to the foreground.
kill [PID]	Kills a process by its Process ID (get from ps).
kill -9 [PID]	Force-kills a stubborn process.

alias fs=./script.sh	Creates a shortcut fs to run your script.
unalias fs	Removes the fs alias.
tar -zcvf a.tar.gz [dir]	Tape Archive: zip, create, verbose, file. Compresses [dir].
tar -xzvf a.tar.gz	Extracts (unzips) the .tar.gz file.
ssh [user]@[host]	Secure Shell. Logs into a remote server.
scp [file] [user]@[host]:~	Secure Copy. Sends [file] to the remote host's home (~) dir.
logout	Logs out of an ssh session.

du -h	Disk Usage for current dir, in human-readable format.
df -h	Disk Free space for all volumes, in human-readable format.
apt install [name]	(Debian/Ubuntu) Installs software.
apt update	(Debian/Ubuntu) Updates the list of available software.
yum install [name]	(RedHat/CentOS) Installs software.

A file like firstScript.sh. Run with ./firstScript.sh after chmod 755.

#!/bin/bash
# ^ This is the "shebang", tells the OS to use bash

i=1
echo "Enter a number: "
read a # Read user input into variable 'a'

# Check if input is a positive integer
if ! [[ $a =~ ^[0-9]+$ ]] || (( a < 1 )); then
   echo "Error: please enter a positive integer." >&2
   exit 1
fi

while [[ $i -le $a ]]; do
   echo "$i"
   if (( i % 2 == 0 )); then
       echo "$i is divisible by 2"
   else
       echo "$i is odd"
   fi

   if (( i % 6 == 0 )); then
       echo "$i is divisible by 6"
   fi
   (( i += 1 )) # Increment 'i'
done

ls # Runs 'ls' at the end of the script

pwd or Get-Location	Print Working Directory (shows where you are).
$env:USERNAME	Shows your account username.
cd [dir] or Set-Location	Change Directory. Use cd .. to go up, cd ~ to go home.
cd -	(PowerShell 7+) Go to the previous directory.
ls or Get-ChildItem	List files and directories.
ls -Hidden	List hidden files and directories.
ls -Force	Lists all items, including hidden and system files.
ls -Recurse	Lists items recursively (in subfolders).
Get-History	Shows command history.
Up Arrow	Scroll through last-used commands.
Tab	Auto-completes filenames or commands.
clear or cls	Clears the terminal screen.
Get-Help [cmd]	Shows the help for a command (e.g., Get-Help ls).
Get-Command [cmd]	Shows the full path to a command (e.g., Get-Command ls).

New-Item -Type Dir [name]	Creates a new Directory.
New-Item -Type File [file]	Creates a new, empty File.
cp [src] [dest] or Copy-Item	Copy an item.
cp -Recurse [src] [dest]	Copy recursively (copies a whole directory).
mv [src] [dest] or Move-Item	Move an item.
Rename-Item [src] [new]	Renames an item (e.g., mv file.txt new.txt).
rm [file] or Remove-Item	Remove an item. Prompts for confirmation.
rm -Recurse -Force [dir]	Removes a directory recursively and forces deletion (no prompt).

echo "text" or Write-Host "text"	Prints "text" to the terminal.
cat [file] or Get-Content	Dumps the entire file content to the screen.
more [file]	View a file one page at a time.
cat -Head 10 [file]	Shows the first 10 lines (head) of a file.
cat -Tail 10 [file]	Shows the last 10 lines (tail) of a file.
notepad [file]	Opens the file in Notepad.

ls -Recurse -Filter "*.txt"	Finds all .txt files recursively.
Select-String "term" [file]	Searches for "term" inside a file. (Like grep).
Get-Content [file] | Sort-Object	Sorts the lines of a file alphabetically.
| (Pipe)	Pipeline. Uses the output of one command as the input for another.
cat f.txt | Sort-Object | Select-String "e"	Example: Gets content, sorts it, then pipes to Select-String.
> (Redirect)	Redirects output to a file (overwrites).
ls > files.txt	Example: Puts the output of ls into files.txt.
>> (Append)	Redirects output to a file (appends to end).
< (Input)	Redirects standard input from a file.
Get-Content name.txt | ./reader.exe	Example: Feeds name.txt to reader.exe.

File permissions are usually managed via the File Explorer GUI (Right-click > Properties > Security).

Get-ExecutionPolicy	Shows if you are allowed to run scripts.
Set-ExecutionPolicy [Policy]	Changes the policy. (e.g., Restricted, RemoteSigned).
Set-ExecutionPolicy Unrestricted -Scope CurrentUser	Allows running scripts for just your user.
./myScript.ps1	To run a PowerShell script, you must use ./

Test-Connection [host]	Pings a host (e.g., Test-Connection 8.8.8.8).
tracert [host]	Traces the network route to a host.
Get-NetIPAddress	Shows network IP addresses (like ip addr).
ipconfig	(Cmd.exe command, but works) Shows network configuration.
Get-Process	Shows your active processes. (Like ps).
Stop-Process -Name [name]	Stops a process by its name.
Stop-Process -Id [PID]	Stops a process by its Process ID.
Start-Job { [cmd] }	Starts a command as a background job.
Get-Job	Lists background jobs.
Receive-Job [ID]	Gets the output of a completed background job.

Compress-Archive [path] [zip]	Creates a .zip file from a folder.
Expand-Archive [zip] [dest]	Unzips a .zip file.
scp [file] [user]@[host]:~	Secure Copy. Sends [file] to a remote host. (Requires SSH client).
chkdsk	Checks Disk for errors.
Get-Volume	Shows disk volumes and free space (like df).
hostname	Shows the computer's name.

winget search [name]	(Windows Package Manager) Searches for software.
winget install [name]	(Winget) Installs software.
choco search [name]	(Chocolatey) Searches for software.
choco install [name]	(Chocolatey) Installs software.

A file like firstScript.ps1. Run with ./firstScript.ps1.

# Variables in PowerShell start with $
Write-Host "Enter a number"
$number = Read-Host # Read user input

$i = 1

while ($i -le $number) { # -le means "Less than or Equal"
    Write-Host "$i"
    
    if ($i % 2 -eq 0) { # -eq means "Equal"
        Write-Host "$i is even baby"
    } else {
        Write-Host "$i odd stuff..."
    }
    
    # -and operator
    if (($i % 2 -eq 0) -and ($i % 3 -eq 0)) {
        Write-Host "number $i is divisable by 6"
    }
    
    $i++ # Increment 'i'
}

# Runs 'ls' at the end of the script
ls