AZ-104 Phase 3 — Shell Reference

PowerShell vs Bash

Sorted by frequency. The Azure CLI (az ...) works identically in both — only the surrounding shell syntax differs.

PowerShell — Windows terminal / pwsh

Bash — Cloud Shell default / Linux/macOS

Quick "which shell am I in?" test: type $PSVersionTable — if it returns a version table, you're in PowerShell. If you see an error, you're in Bash. Azure Cloud Shell defaults to Bash; local Windows terminals usually default to PowerShell.

Frequency	Concept	PowerShell	Bash
Variables & output — you'll see these in every script
Very high	Variables Assignment & use	`$name = "east-us"` Always $ on both sides	`name="east-us"` → read as `$name` No $ on left; $ only when reading
Very high	Print to screen	`Write-Host "hello"` or just type the value	`echo "hello"`
Very high	Capture output Command → variable	`$rg = az group list`	`rg=$(az group list)`
String building — constructing resource names & IDs
Very high	Embed variable in string	`"rg-$name"` Double quotes expand; single quotes are literal	`"rg-$name"` or `"rg-${name}"` Same double/single rule
Medium	Multi-line command	` backtick at line end	`\` backslash at line end
Environment & shell identity
Very high	Environment variables	`$env:HOME` / `$env:PATH`	`$HOME` / `$PATH`
Very high	Pipeline Chain commands	`cmd \| Select-Object Name` Passes structured objects	`cmd \| grep "name"` Passes plain text
Medium	Which shell am I in?	`$PSVersionTable`	`echo $SHELL` or `ps -p $$`
Control flow — conditionals & loops
Medium	If / else	`if ($x -eq "val") { ... }` Operators: -eq -ne -gt -lt	`if [ "$x" = "val" ]; then ... fi` Operators: = != -gt -lt
Medium	For loop	`foreach ($i in $list) { ... }`	`for i in "${list[@]}"; do ... done`
Less common — recognise, don't memorise
Lower	Functions	`function Greet { param($n) "Hi $n" }`	`greet() { echo "Hi $1"; }`
Lower	Error handling	`try { ... } catch { ... }`	`cmd \|\| echo "failed"` or `set -e`
Lower	Here-string Multi-line literal	`@"...multi-line..."@`	`<<EOF ... EOF`

Pattern	What to run	When to use it
Finding the right az command — drill-down with --help
Step 1 — find the service group	`az monitor --help` Lists all subgroups under az monitor	You know the service (monitor, network, keyvault) but not the subgroup. Read the list — log-analytics, diagnostic-settings, etc will appear.
Step 2 — find the noun	`az monitor log-analytics --help` Shows subgroups: workspace, cluster, etc	Drill into the subgroup. Each level narrows further until you reach commands (show, create, delete, list).
Step 3 — find the flags	`az monitor log-analytics workspace show --help` Shows all flags, required vs optional, and examples	The final --help shows every flag. Required flags are marked. Examples section at the bottom is the fastest path to correct syntax.
Finding JSON shapes — use show before create
show an existing resource Get the exact JSON shape Azure expects	`az monitor diagnostic-settings show \ --resource $RESOURCE_ID` Returns the full JSON of an existing setting	When --help says "JSON encoded list" but gives no example: run show on an existing resource first. Copy that JSON shape into your create command. This works for --logs, --metrics, --rules, and any other complex JSON flag.
list available categories Find valid values for --logs categories	`az monitor diagnostic-settings categories list \ --resource $RESOURCE_ID \ --query "[].{name:name,type:categoryType}" -o table`	Every resource type exposes different log categories (AuditEvent, StorageRead, AppServiceHTTPLogs, etc). This command returns exactly what is valid for that specific resource — no guessing.
Flag shorthand — both forms are always valid
Common shorthand flags	`-g` = `--resource-group` `-n` = `--name` `-l` = `--location` `-o` = `--output`	Azure CLI defines shorthand aliases for the most common flags. Both forms work identically — -g rg-name and --resource-group rg-name produce the same result. Use shorthand in scripts you run often, full form when readability matters.

PowerShell pipeline

Commands pass structured objects — like handing someone a filled-out form with labelled fields.

You can ask for a specific field by name: | Select-Object Name

Bash pipeline

Commands pass plain text — like handing someone a sticky note. You parse it yourself.

You use text tools to find what you need: | grep "name"