Module 2 · OverviewBy the end of this module you can…

GUI vs. CLIWhy programmers type instead of clicking

VocabularyTerminal, shell, console — what’s the difference?

Analogy: the terminal is a web browser; the shell is the website you’re visiting. One Windows Terminal window can host tabs of PowerShell, cmd, and even Linux (WSL).

SetupInstall Windows Terminal & modern PowerShell

winget install --id Microsoft.PowerShell -e

SetupTwo PowerShells? Here’s the difference

Check which one you’re in:

PS C:\Users\Jane> $PSVersionTable.PSVersion

Major  Minor  Patch
-----  -----  -----
7      4      6

First lookReading the prompt

PS C:\Users\Jane> _

NavigationThe big three: pwd, ls, cd

PS C:\Users\Jane> pwd

Path
----
C:\Users\Jane

PS C:\Users\Jane> cd C:\actuarial_work\sandbox
PS C:\actuarial_work\sandbox> ls

    Directory: C:\actuarial_work\sandbox

Mode          LastWriteTime   Length Name
----          -------------   ------ ----
d----   09/29/2026  10:14 AM         data
d----   09/29/2026  10:14 AM         notebooks
-a---   09/29/2026  10:20 AM       16 model.py

Navigationcd patterns you’ll use every day

Forward slashes work too: cd C:/actuarial_work/sandbox.

Under the hoodAliases: short names for long commands

PS> Get-Alias ls

CommandType  Name
-----------  ----
Alias        ls -> Get-ChildItem

The #1 habitTab-completion

Never type a full path. Type a few letters, then press Tab.

PS C:\> cd act⇥          →   cd .\actuarial_work\
PS C:\> cd .\actuarial_work\sa⇥   →   cd .\actuarial_work\sandbox\

File operationsCreate, copy, move, delete

mkdir pricing                                 # new folder
mkdir pricing\data\raw                        # creates nested folders in one go
New-Item -ItemType File pricing\README.md     # new empty file (short form: ni)

cp C:\Users\Jane\Downloads\claims.csv pricing\data\raw\     # copy a file in
cp pricing\data -Destination backup_data -Recurse          # copy a whole folder

mv pricing\data\raw\claims.csv pricing\data\claims_2025.csv  # move AND rename
mv notes.txt old_notes.txt                                  # rename in place

rm old_notes.txt                              # delete a file
rm backup_data -Recurse                       # delete a folder and everything inside

SyntaxAnatomy of a command

Get-ChildItem C:\actuarial_work -Filter *.csv -Recurse

Get-Help Copy-Item -Examples
Get-Command *item*        # find commands by name
python --help             # most other tools

SyntaxPaths with spaces need quotes

PS> cd C:\Users\Jane\OneDrive - Contoso\Documents
Set-Location: A positional parameter cannot be found
that accepts argument '-'.

cd "C:\Users\Jane\OneDrive - Contoso\Documents"
cd 'C:\Program Files'

& "C:\Program Files\Git\bin\git.exe" --version

ViewingLook inside files without opening an app

cat data\claims.csv                    # whole file (Get-Content)
cat data\claims.csv -Head 5            # first 5 lines — perfect for peeking at big CSVs
cat logs\run.log -Tail 20              # last 20 lines
cat data\claims.csv | more             # one screen at a time (Space = next, q = quit)

Select-String "LAPSE" data\*.csv       # search inside files (like Ctrl+F across many files)
Select-String "error" logs\*.log -CaseSensitive

PipesThe pipe |: output of one → input of the next

Get-ChildItem C:\actuarial_work -Recurse -File |
    Where-Object Length -gt 1MB |
    Sort-Object Length -Descending |
    Select-Object -First 5 Name, Length

cat data\claims.csv | Select-String "MOTOR" | Measure-Object   # how many motor claims?

PowerShell pipes objects (with properties like Name, Length), not just text. That’s why Sort-Object Length just works.

RedirectionSave output to a file: > and >>

ls data > inventory.txt          # create / OVERWRITE
Get-Date >> run_log.txt          # APPEND a line
python model.py 2> errors.txt    # save only error output

Select-String "LAPSE" data\*.csv > lapses.txt

Muscle memoryKeyboard shortcuts every developer uses

Muscle memoryCtrl+C: the emergency brake

PS> ping -t localhost

Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
...                         ← press Ctrl+C
Control-C
PS> _

ReferenceCheat sheet

RecapModule 2 checklist

• Windows Terminal is pinned and opens PowerShell 7 by default
• I can explain terminal vs. shell
• I can navigate anywhere with cd, ls, pwd — using Tab
• I can create, copy, move, rename, and delete files and folders (and I respect rm)
• I can read a command: command, arguments, flags, quotes
• I can pipe with | and redirect with > / >>
• Ctrl+C and ↑ are already reflexes