win-dat

network scan

PS C:\Users\Administrator> nmap -p 22 192.168.141.0/24
Starting Nmap 7.98 ( https://nmap.org ) at 2026-05-14 15:19 +0800
Nmap scan report for 192.168.141.98
Host is up (0.0089s latency).

PORT   STATE  SERVICE
22/tcp closed ssh
MAC Address: 32:97:37:31:8B:2B (Unknown)

Nmap scan report for 192.168.141.142
Host is up (0.010s latency).

PORT   STATE  SERVICE
22/tcp closed ssh
MAC Address: 9C:47:82:E9:EA:56 (TP-Link Technologies)

Nmap scan report for 192.168.141.250
Host is up (0.15s latency).

PORT   STATE  SERVICE
22/tcp closed ssh
MAC Address: D6:A1:27:1D:34:0B (Unknown)

Nmap scan report for 192.168.141.106
Host is up (0.0010s latency).

PORT   STATE  SERVICE
22/tcp closed ssh

Nmap done: 256 IP addresses (4 hosts up) scanned in 13.16 seconds

set the permanent environment variables The Command Line Way (setx)

The setx command is the standard way to set permanent variables directly from the Command Prompt.

For the Current User: setx VAR_NAME "your_value"

For the Entire System (Requires Admin): setx VAR_NAME "your_value" /M

Note: When you use setx, the variable is saved to the Registry, but it will not appear in the current CMD window you are using. You must close and reopen the Command Prompt to see the change.

set variable - first

setx avrdude "C:\Users\Administrator\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17\bin\avrdude.exe" /M
setx avrdude_conf "C:\Users\Administrator\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17\etc\avrdude.conf" /M

then run

%avrdude% -C %avrdude_conf% -v -p m328p -c avrispmkii -P usb -D -Uflash:w:optiboot_lgt8f328p.hex:i

cancel setx

The "Empty String" Trick (CMD)

You can't truly delete a variable with setx, but you can strip it of its value. This leaves the variable name in the registry but makes it empty.

setx VAR_NAME ""

ref

OS-dat - linux-dat