All posts by Roman

APC Back-UPS 1400 (BX1400UI)

September 10, 2025NUT, UPSRoman

Battery replacement

I was able to get battery replacement at alza.cz.

Replacing the batteries in this UPS is not very easy.

NUT tools configuration

[ups]
  driver = usbhid-ups
  port = auto
  desc = "APC Back-UPS BX1400UI"

Create bootable Windows installation USB from Linux

September 9, 2025Arch Linux, Linux, WindowsRoman

Download Ventoy from Github and extract it.

Install Ventoy to USB: sudo ./Ventoy2Disk.sh -i /dev/sdX

Copy Windows installation ISO to USB: cp Win11.iso /run/media/$USER/Ventoy/

Migrate Debian Buster (10) APT to Archive

September 8, 2025DebianRoman

The following script replaces repository URLs to allow installation of apps on this legacy Debian version.

sed -i \
    -e 's|deb.debian.org/debian-security|archive.debian.org/debian-security|g' \
    -e 's|deb.debian.org/debian|archive.debian.org/debian|g' \
    /etc/apt/sources.list

Download Gravatar image from CLI

September 3, 2025Gravatar, LinuxRoman

First you need to compute hash of your e-mail.

echo -n "john.doe@example.com" | sha256sum

Than you can download it using curl. Replace HASH with the output from the previous command.

curl -fL "https://www.gravatar.com/avatar/HASH?s=500&d=404" -o avatar.jpg

Parameters

s=500 (Gravatar supports 1–2048px size)
d=404 (If there is no image return HTTP 404)
r=pg|r|x (To change rating)

See more information on Gravatar docs.

Fetch hardware info from CLI

August 28, 2025Arch Linux, LinuxRoman

Neofetch is no longer supported, but there is actively maintened alternative called fastfetch for fetching system information and displaying it in a visually appealing way.

sudo pacman -S fastfetch

Replace text in multiple files

August 20, 2025Linux, WindowsRoman

Using find and sed a text in multiple files can be replaced using a one liner. If you have GIT bash you can do it in Windows too.

In the example below address of old.server.com will be replaced with new.server.com in all Web.config files.

find /c/inetpub/wwwroot -name "Web.config" -exec sed -i 's/old.server.com/new.server.com/g' {} +

Upgrade Debian 11 to Debian 12

August 12, 2025DebianRoman

I use those steps on LXC virtual in Proxmox:

Make sure all packages are upgraded: apt update && apt upgrade
Backup container in Proxmox
Edit release version: sed -i'.bak' 's/bullseye/bookworm/g' /etc/apt/sources.list
Update other configuration files in /etc/apt/sources.list.d/ appropriately
Update packages index: apt update
Do minimal system upgrade: apt upgrade --without-new-pkgs
Do full upgrade: apt full-upgrade
Restart the system: reboot

See detailed instructions here.

Yubikey FIDO2 SSH and MacOS

August 7, 2025MacRoman

Even on MacOS Sequoia ssh does not support FIDO2. You need to install openssh using brew, otherwise you may get error Cannot download keys without provider when you try to import resident keys from Yubikey using ssh-keygen -K.

After you install openssh brew install openssh, restart terminal and make sure which ssh displays /opt/homebrew/bin/ssh.

Another problem that you may face, which is not related to MacOS is error Provider "internal" returned failure -1. The problem is that you may generate SSH key on Yubikey without FIDO PIN. But if you do not set FIDO PIN, you cannot import the key. Fortunately you can set the PIN later.

ykman fido access change-pin

Edit files in Altap Salamander using nano

August 5, 2025Git, Linux, WindowsRoman

This guide is meant for those who need to work in Windows from time-to-time and would like to have linux feeling.

Prerequisites

In Altap Salamander go to Configuration -> Editors.

Command	`"C:\Program Files\Git\bin\bash.exe"`
Arguments	`--login -i -c 'nano "$(Name)"'`
Initial Directory	`$(FullPath)`

Remarks

--login -i is used to start interactive shell.

-c starts a command (nano …)

nmcli

July 25, 2025Cheat Sheet, LinuxRoman

Basic Commands

Command	Description
`nmcli`	Show general help
`nmcli general status`	Show overall NetworkManager status
`nmcli general hostname`	View or set system hostname
`nmcli radio all`	Show Wi-Fi and Bluetooth state
`nmcli networking on/off`	Enable or disable all networking
`nmcli connection show`	List saved connections
`nmcli device status`	Show status of all devices

Device Management

Command	Description
`nmcli device`	List all devices
`nmcli device show`	Show detailed info for all devices
`nmcli device disconnect <device>`	Disconnect a specific device (e.g. `wlan0`)
`nmcli device connect <device>`	Connect a specific device

Wi-Fi

Command	Description
`nmcli device wifi list`	List available Wi-Fi networks
`nmcli device wifi connect <SSID> password <password>`	Connect to a Wi-Fi network
`nmcli device wifi connect <SSID> --ask`	Connect to a Wi-Fi network and ask for password
`nmcli connection show --active`	Show active connections
`nmcli connection up <name>`	Activate a connection
`nmcli connection down <name>`	Deactivate a connection

Connections (Profiles)

Command	Description
`nmcli connection add type ethernet ifname eth0 con-name home`	Add new Ethernet connection
`nmcli connection modify <name>`	Modify connection settings
`nmcli connection delete <name>`	Delete a saved connection
`nmcli connection clone <name> <new_name>`	Clone a connection profile

Reset and Troubleshooting

Command	Description
`nmcli connection reload`	Reload all connection profiles
`nmcli networking off && nmcli networking on`	Restart networking
`nmcli --ask`	Prompt for password or secrets interactively