# OS-4: Windows Command Line

Status: not started

Domain:
- 1.0 Operating Systems

Objective alignment:
- 1.5 Windows command-line tools
- 1.7 Windows networking basics
- 3.1 Windows troubleshooting support

## What You Need To Know

Core 2 command questions usually ask, "Which command would you use?"

Think in buckets:
- **Navigation**: move around files and folders.
- **Network**: check IP address, connectivity, DNS, routes, and connections.
- **Disk/file repair**: check file systems and system files.
- **Identity/system info**: computer name, signed-in user, Windows version.
- **Group Policy**: update or report applied policies.
- **Help**: find command syntax.

Some commands are safe to run anytime. Others can change disks or files, so use them carefully.

## Memory Tricks

- **`ipconfig` = IP configuration.**
- **`ping` = "Are you alive?"**
- **`tracert` = trace route.**
- **`nslookup` = name server lookup.**
- **`netstat` = network statistics.**
- **`chkdsk` = check disk.**
- **`sfc` = system file checker.**
- **`gpupdate` = Group Policy update.**
- **`gpresult` = Group Policy result.**
- **`/?` = "How do I use this?"**

## Commands To Enter

Enter these on Windows PowerShell or Command Prompt.

### Navigation

```powershell
dir
```

What it does:
- Lists files and folders in the current directory.
- Similar Linux command: `ls`.

```powershell
cd
```

What it does:
- Shows or changes the current directory.
- `cd ..` moves up one folder.

```powershell
mkdir test-folder
```

What it does:
- Creates a folder named `test-folder`.
- `md` does the same thing.

```powershell
rmdir test-folder
```

What it does:
- Removes an empty folder.
- `rd` does the same thing.

### Network

```powershell
ipconfig
```

What it does:
- Shows IP address, subnet mask, and default gateway for network adapters.

```powershell
ipconfig /all
```

What it does:
- Shows detailed adapter info, including MAC address, DNS servers, DHCP status, and lease details.

```powershell
ping 127.0.0.1
```

What it does:
- Tests the local TCP/IP stack using the loopback address.
- If this fails, the local networking stack has a problem.

```powershell
ping 8.8.8.8
```

What it does:
- Tests basic IP connectivity to an external address.
- If this works but names do not, suspect DNS.

```powershell
nslookup example.com
```

What it does:
- Queries DNS for a hostname.
- Useful when websites fail by name but IP connectivity works.

```powershell
tracert example.com
```

What it does:
- Shows the router hops toward a destination.
- Useful for finding where a path may stop.

```powershell
pathping example.com
```

What it does:
- Combines route tracing with packet-loss statistics.
- Takes longer than `tracert`.

```powershell
netstat -ano
```

What it does:
- Shows active connections and listening ports.
- `-a` shows all connections/listeners.
- `-n` keeps addresses numeric.
- `-o` shows process IDs.

### Disk and File Repair

```powershell
chkdsk
```

What it does:
- Checks the disk file system status.

```powershell
chkdsk /f
```

What it does:
- Fixes logical file system errors.
- May need to run at startup if the drive is locked.

```powershell
chkdsk /r
```

What it does:
- Looks for bad sectors and recovers readable information.
- Includes `/f`.
- Can take a long time.

```powershell
sfc /scannow
```

What it does:
- Scans protected Windows system files and repairs them when possible.

### Identity and System Info

```powershell
hostname
```

What it does:
- Shows the computer name.

```powershell
whoami
```

What it does:
- Shows the current user.

```powershell
whoami /all
```

What it does:
- Shows current user, groups, privileges, and security identifier details.

```powershell
winver
```

What it does:
- Opens the Windows version/build dialog.

### Group Policy

```powershell
gpupdate /force
```

What it does:
- Forces a Group Policy refresh.
- Most relevant on domain-joined business systems.

```powershell
gpresult /r
```

What it does:
- Shows Resultant Set of Policy summary for the user/computer.
- Use it to verify what policies applied.

### Help

```powershell
ipconfig /?
```

What it does:
- Shows help and syntax for `ipconfig`.
- Most Windows commands support `/?`.

```powershell
help dir
```

What it does:
- Shows help for the `dir` command.

## Commands To Know But Treat Carefully

```powershell
format
```

What it does:
- Formats a volume.
- Warning: this can erase data.

```powershell
diskpart
```

What it does:
- Opens a powerful disk partitioning tool.
- Warning: incorrect commands can erase partitions or make a system unbootable.

```powershell
robocopy
```

What it does:
- Copies files and folders robustly.
- Useful for backups and migrations.
- Be careful with mirror options because they can delete destination files.

## Linux Comparison Commands

```bash
ls
pwd
cd
mkdir test-folder
rmdir test-folder
ip addr
ping 127.0.0.1
traceroute example.com
dig example.com
df -h
du -h
ps aux
top
```

Why this matters:
- Linux command practice helps you understand the same troubleshooting ideas across operating systems.
- Exact commands differ, but the goal is often the same: identify the system, check network state, inspect storage, and view running processes.

## Mini Lab

Goal:
- Practice safe command-line troubleshooting.

Windows:
1. Run `hostname`.
2. Run `whoami`.
3. Run `winver`.
4. Run `ipconfig`.
5. Run `ipconfig /all`.
6. Run `ping 127.0.0.1`.
7. Run `nslookup example.com`.
8. Run `netstat -ano`.
9. Run `sfc /scannow`.
10. Run `ipconfig /?`.

Record:
- Computer name:
- Current user:
- IPv4 address:
- Default gateway:
- DNS server:
- Did loopback ping work?
- Did DNS lookup work?
- One listening port from `netstat -ano`:

Linux:
1. Run `hostname`.
2. Run `whoami`.
3. Run `ip addr`.
4. Run `ping -c 4 127.0.0.1`.
5. Run `df -h`.
6. Run `ps aux`.
7. Run `top`, then press `q`.

Record:
- Hostname:
- Current user:
- IP address:
- Root filesystem free space:
- One running process:

## Quick Check Before Quiz

You are ready for the OS-4 quiz when you can answer these without looking:
- Which command shows full Windows IP configuration?
- Which command tests DNS name resolution?
- Which command shows active connections and process IDs?
- Which command repairs protected Windows system files?
- Which command forces Group Policy refresh?
- Which commands can erase data if misused?