Thomas' Wiki

Automatically assigning extensions to files - created

thomas (thomas@undisclosed.example.com) — 2026-02-23T10:39:37+00:00

Automatically assigning extensions to files #recursively find files in current directory that have no extension for i in $(find . -type f ! -name "*.*"); do #guess that extension using file extfile=$(file --extension --brief $i) #select the first extension in the event file spits something weird (e.g. jpeg/jpe/jfif) extawk=$(echo $extfile | awk -F/ '{print $1}') #copy the file to a file appended with the extension guessed from the former commands mv $i $i.$extawk done

Setting SPF and DMARC for a domain that is not sending e-mail - created

thomas (thomas@undisclosed.example.com) — 2025-12-17T08:39:00+00:00

Setting SPF and DMARC for a domain that is not sending e-mail Set the SPF TXT record (domain.com) to: v=spf1 -all This will inform receiving mail servers that no servers are authorized to send mail from this domain. Set the DMARC TXT record (_dmarc.domain.com) to:

Generating hashes from a string with a Yubikey

thomas (thomas@undisclosed.example.com) — 2024-12-12T21:54:15+00:00

Generating hashes from a string with a Yubikey Use Yubikey authenticator to set up a challenge-response algorithm in slot 2 of your Yubikey. Then, make sure you have the command line tool ykchalresp installed. It usually comes packaged with the Yubikey personalization tool, e.g. on macOS via Homebrew:

Common OpenSSL Operations

thomas (thomas@undisclosed.example.com) — 2024-11-20T08:38:05+00:00

Common OpenSSL Operations Extracting a private key in PEM format from a P12 container openssl pkcs12 -in container.p12 -out key.pem -legacy -nocerts -nodes Extracting a certificate in PEM format from a P12 container openssl pkcs12 -in container.p12 -out certificate.pem -legacy -nokeys -nodes

Da Rules - created

thomas (thomas@undisclosed.example.com) — 2024-11-13T22:40:39+00:00

Da Rules * Nothing is more permanent than a temporary solution. * Meetings with more than 4 people are rather pointless. * Avoid starting from scratch. Incrementally improve what already exists.

Parsing a CSV File with Bash - [References]

thomas (thomas@undisclosed.example.com) — 2024-11-09T10:06:49+00:00

Parsing a CSV File with Bash You can easily parse CSV files with bash. In this example script, I generate QR codes using qrencode as an example. As a source I use following very simple CSV file called list.csv: Google,https://www.google.com Yahoo,https://www.microsoft.com Microsoft,https://www.microsoft.com

List libvirt OS Variants - [References]

thomas (thomas@undisclosed.example.com) — 2024-11-08T10:19:32+00:00

List libvirt OS Variants When creating a guest with virt-install you need to specify the --os-variant. To get a list of acceptable values, first install the libosinfo-bin package sudo apt install libosinfo-bin before running the command below:

Logging in on Windows 11 Remote Desktop with Your Microsoft Account - created

thomas (thomas@undisclosed.example.com) — 2024-11-07T12:02:15+00:00

Logging in on Windows 11 Remote Desktop with Your Microsoft Account On Windows 11, if you use your Microsoft account to log in to your PC, you will be unable to log in via Microsoft Remote Desktop. As a workaround, you need to use runas to cache your Microsoft account password. After that (and of course enabling Remote Desktop), you will be able to log in remotely using your Microsoft account e-mail address and password

Listing all Teams assigned phone numbers

thomas (thomas@undisclosed.example.com) — 2024-11-07T10:50:39+00:00

Listing all Teams assigned phone numbers :!: At the time of writing, this does not yet seem possible with Graph API, and requires the Teams Powershell module instead. Open PowerShell, and install the PowerShell Teams module: Install-Module -Name MicrosoftTeams -Force -AllowClobber

Working with docker - created

thomas (thomas@undisclosed.example.com) — 2024-10-24T20:44:15+00:00

Working with docker Getting a shell in a running container: docker exec -it containername bash

- removed

thomas (thomas@undisclosed.example.com) — 2024-10-15T20:28:16+00:00

macos_version_in_disk_utility.png - created

thomas (thomas@undisclosed.example.com) — 2024-03-26T11:01:33+00:00

yubikey_challenge-response.png - created

thomas (thomas@undisclosed.example.com) — 2024-03-19T22:23:13+00:00

purge_stale_devices.ps1 - created

thomas (thomas@undisclosed.example.com) — 2024-03-15T09:03:25+00:00