koldfront

open-qr-code #shell

It's not that often I encounter a QR code I want to open on my computer, but when I do it would be nice to simply be able to select the graphic on the screen, and then have the URL open.

Combining Flameshot and zbar-tools in a small shell script allows me to do just that: the script checks for PNG in the clipboard, and if there is none, launches Flameshot. After that zbarimg is run to extract the URL, which is then opened in the default browser:

#!/bin/sh

# open-qr-code - script to interpret a qr-code in the clipboard and
#                open it.
#
#     Depends on: xclip, zbar-tools, libnotify-bin, flameshot.

# 1) Save png from clipboard in file:
CAPTURE=0
if ! xclip -o -t TARGETS -selection clipboard | grep --quiet image/png; then
    # 0) If there is no image in clipboard, launch flameshot to pick one:
    sed -i 's/showDesktopNotification=true/showDesktopNotification=false/' ~/.config/flameshot/flameshot.ini
    flameshot gui --clipboard --accept-on-select
    sed -i 's/showDesktopNotification=false/showDesktopNotification=true/' ~/.config/flameshot/flameshot.ini
    CAPTURE=1
fi
if xclip -o -t TARGETS -selection clipboard | grep --quiet image/png; then
    IMAGE=$(/bin/mktemp --tmpdir qr-codeXXXXXX.png)
    xclip -t image/png -selection clipboard -o > "$IMAGE"
    # 2) Run QR-code detector:
    if CONTENT=$(zbarimg --quiet "$IMAGE"); then
        # 3) If it is a URL, open it in a browser:
        URL=$(echo "$CONTENT" | sed 's/^QR-Code://')
        if echo "$URL" | grep --quiet '^http'; then
            notify-send --icon /usr/share/icons/Moka/256x256@2x/apps/qr-creator.png "Open QR code" "Opened $URL"
            x-www-browser --new-window "$URL" &
        else
            notify-send --icon /usr/share/icons/Moka/256x256@2x/apps/qr-creator.png "Open QR code" "QR code contained non-url: '$URL'"
        fi
    else
        notify-send --icon /usr/share/icons/Moka/256x256@2x/apps/qr-creator.png "Open QR code" "Did not find a QR code in the image"
    fi
    if [ $CAPTURE = 1 ]; then
        echo "" | xclip -in -selection clipboard
    fi
else
    notify-send --icon /usr/share/icons/Moka/256x256@2x/apps/qr-creator.png "Open QR code" "No image/png in clipboard"
fi

watchfile #shell

Recently I was editing a Markdown file and I was converting it to HTML with pandoc for every edit.

Re-running the command quickly became tedious - I could use some kind of framework for editing Markdown or something elaborate, but what I really wanted was just "run a command when a file changes".

So, watchfile was born - it basically just wraps inotifywait from the inotify-tools package:

#!/bin/sh

# watchfile FILE COMMAND - run a command whenever a file changes.

FILE=$1
shift

while inotifywait --quiet --quiet "$FILE"; do
    echo -n "Running '$*' ... "
    "$@"
    echo "done."
done

dl #shell

One of the small, handy shell scripts I use all the time is called dl. If called with arguments, URLs, it will try downloading each argument using yt-dlp.

That's pretty mundane, basically just easier to spell. But here is the twist: if called without arguments, dl examines the clipboard, looking for a URL, and downloads it if found, then the selection.

So often I will see a link to a video, copy the address and then open a shell, type dl and away we go - skipping the "paste the URl"-step.

Small improvement, but very handy.

P.S. It also retries.

#!/bin/bash

# dl - wrapper to download with yt-dlp from clipboard to ~/video.
#
# Copyright (C) 2020-2025, by Adam Sjøgren  Under the GPLv2.

set -o pipefail

cd ~/video || exit 10

MAX_RETRIES=5

ARGS=( "$@" )
if [ "$*" == "" ]; then
    ARGS[0]=$(xsel --output --clipboard)
    if [[ ${ARGS[0]} != http* ]]; then
        # If not the clipboard, maybe the mouse:
        ARGS[0]=$(xsel --output)
        echo "dl: clipboard is empty, using string from the mouse"
    else
        # Clear clipboard if we got a URL from it, so we are ready for
        # the next, possibly from the mouse:
        echo "dl: using string from the clipboard"
        # This doesn't work, at least not with Emacs:
        #   xsel --clear --clipboard
        # so do this instead:
        echo -n "" | xsel --input --clipboard
    fi
fi

i=0
for url in "${ARGS[@]}"; do
    if [[ "$url" != http* ]]; then
        echo "'$url' doesn't look like a URL"
        exit 10
    fi
    url=$(echo "$url" | sed 's/drtv\/episode\//drtv\/se\//')
    url=$(echo "$url" | sed 's/drtv\/program\//drtv\/se\//')
    if [ $i -gt 0 ]; then
        echo ""
    fi
    FILE=$url
    LAST_ERROR=1
    TRY=1
    echo "Downloading $url ..."
    while ((LAST_ERROR != 0 && TRY < MAX_RETRIES)); do
        if [ $TRY -gt 1 ]; then
            echo "Trying again ($LAST_ERROR, $TRY)"
        fi
        yt-dlp --force-ipv4 --color always --print 'before_dl:%(title)s' --print-to-file before_dl:title "/tmp/dl-out-$$.txt" "$url"
        LAST_ERROR=$?
        FILE=$(cat /tmp/dl-out-$$.txt)
        rm /tmp/dl-out-$$.txt
        TRY=$((TRY + 1))
    done
    if [ $LAST_ERROR != 0 ]; then
        echo "Failed dl $url"
    else
        TITLE=$(ffprobe "$FILE" 2>&1 | grep ' title ' | cut -d: -f2-)
        if [ "$TITLE" == "" ]; then
            TITLE="$FILE"
        fi
        if [ "$TITLE" == "" ]; then
            TITLE="$url"
        fi
        notify-send --icon /usr/share/pixmaps/terminal-tango.svg --expire-time 2000 'dl' "${TITLE} downloaded"
        echo "Done."
    fi
    i=$((i+1))
done

Bridging the fediverse #activitypub #fediverse #illuminant

A couple of years ago I started making an ActivityPub server to make it easy for me to access the fediverse over nntp.

One of the challenges - at least in the way I built my server - is that every server it talks to speaks a slightly different dialect of ActivityPub. Mastodon generates JSON with one structure, Pleroma might include a field that others don't, GotoSocial might leave one out, etc. etc.

Around a month ago Klaus lured me into trying the Bluesky↔Fediverse bridge Bridgy Fed. TechCrunch had a nice introduction on how to bridge your account, which I followed.

And then I had to adjust my ActivityPub server to the quirks of the bridge. Usually it's stuff like "this field I have only ever encountered having a string as the value, but now it's a dictionary, or a list", and it takes me a while to handle all of them.

Had I implemented the spec rather than just building something and trying it against other servers, I would probably have fewer of these surprises. But, hey, I was (and still am) building Illuminant for fun, so I was happy to implement just enough to interact.

One thing that in hindsight is sort of expected and also sort of a downer is that boosts and parent blueskidoos only show up if the sender's account is bridged. So rather than being a useful expanse of the fediverse, this bridging turns out - to me, anyway - to be more of a curiosity than anything else.

Saving and restoring an Emacs macro #emacs

From time to time I add domains to a configuration file, header_checks, for my mail server, Postfix, to block them as spam.

To do this, I copy the email-address from a spam email, paste it into the configuration file, and modify it to escape the . and remove up until the @.

Doing that for a lot of spam is of course tedious, and so I usually create a macro in Emacs to do the pasting and massaging.

However, creating that macro is a bit tedious and that makes me not do it for the first couple of spams. Until I get too annoyed. So it keeps me from updating the checks. Not great.

Emacs is capable of generating the lisp code corresponding to a macro, so I thought "Hah, I will save the macro in a comment in the file, then I can evaluate it when I'm updating the file, and I don't have to record the macro every time!"

Alas, the command M-x insert-kdb-macro RET inserted some code that gave an error when evaluated - how odd?!

At first I assumed I was doing something wrong - the documentation only mentions saving a named macro and I was saving the last, unnamed one - but after looking at the lisp code of the function insert-kbd-macro (Emacs makes this easy), it was clear to me that it was supposed to work: it contains specific code to handle the last macro case.

I also tried an earlier version of Emacs (I usually run a development version), the one in Debian stable - version 28.2, and there the code generated was different, and, even more interestingly, worked!

So, I created a bug report for Emacs (#77317) and was swiftly told by one of the current Emacs maintainers that the documentation only says it works for named macros.

I argued that the function specifically has a branch for the last (and unnamed) keyboard macro, and that the functionality was broken in 2022, and Cc'ed the previous Emacs maintainer who made the breaking change (which was an improvement to the other branch of the function).

He asked for an explanation of my use case, and after I supplied that, he made a change to fix the problem, which I tested swiftly; it worked, and pushed it to the development version of Emacs a couple of days later.

Nice!

So, now I could easily generate the code to restore the macro and put it in a comment in the file.

Shortly after it hit me: Emacs can evaluate code from a file when loading it, I could have it restore the macro automatically on opening the file!

A quick 3 lines at the bottom of the file later:

# Local Variables:
# eval: (setq last-kbd-macro (kmacro--keys (kmacro "| C-y M-<left> <left> [ <right> ] C-r @ <right> M-<backspace> C-s ) <left>")))
# End:

and now, more than ever, Bob is indeed my uncle!