TIL - raw HTML in Hugo

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

I'm using Hugo [1] for this website setup [2] and find very satisfying. I can write all my content in reStructured Text [3] and create a website out from it.

Today I needed to add a part of raw HTML into one of my pages and that was when I found Shortcodes [4] in Hugo which is very useful.

It is also easy to create your own shortcodes. In my case, I created layouts/shortcodes/rawhtml.html containing:

<!-- raw html -->
{{.Inner}}

Now I can add raw HTML to my pages by using the rawhtml tag, for examle:

{< rawhtml >}
<iframe width="100%" height="500" src="https://docs.google.com/spreadsheets/d/e/2PACX-1vT_kO5y3AssyITYdDszNhORVHz5xAWf-WLcKuh50XV-fGqWTaIz9ICT1c0fGrqyl5U-3dAGXaoDkWlY/pubhtml?gid=0&amp;single=true&amp;widget=true&amp;headers=false"></iframe>
{< / rawhtml >}

Which will end up like:

Of course, this isn't the best ( nor safest) way to use shortcodes. There are several reference implementations [5] in the repository that may be worth a look.

TIL - Parse command output from shell

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

Parse text output in shell scripts is something that is needed every now and then. It used to be some clever pipeline with regular expressions, grep, cut or even awk.

But now I've started to use read for such things, and it has helped me a lot.

Consider the following example:

$ mmcli  -L
     /org/freedesktop/ModemManager1/Modem/0 [Sierra Wireless] HL7812

Some parts of this string are dynamic, namely ModemManager1, 0 and [Sierra Wireless] HL7812.

So, If I want to parse and store these strings into variables, I could simple do:

$ IFS='/ ' read -r _ _ _ mm _ mn mt < <(mmcli -L)

• IFS='/ ' Sets / or space as input field separators
• read -r _ _ _ mm _ mn mt: Read 4th, 6th and 7th onwards test in variable mm, mn and mt while ignoring rest
• < <(mmcli -L): Command substitution to invoke mmcli -L and feed it's output to read

This result is stored in mm, mn and mt:

$ declare -p mm mn mt
declare -- mm="ModemManager1"
declare -- mn="0"
declare -- mt="[Sierra Wireless] HL7812"

Pretty neat.

TIL - Reuse your SSH connection

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

OpenSSH has the feature to reuse an existing SSH connection for multiple subsequent connections to the same host. It will improve your workflow because it reduces the time it takes to establish a new connection and in cases where you have to type a password, the time saving is even more.

The feature is ControlMaster and is documented in ssh_config(5) [1]:

ControlMaster
Enables the sharing of multiple sessions over a single network connection.
When set to ''yes'', ssh(1) will listen for connections on a control
socket specified using the ControlPath argument.  Additional sessions
can connect to this socket using the same ControlPath with ControlMaster
set to ''no'' (the default).  These sessions will try to reuse the
master instance's network connection rather than initiating new ones,
but will fall back to connecting normally if the control socket does not
exist, or is not listening.

To make use of this feature add the following line to your ~./ssh/config file:

Host *
        ControlMaster auto
        ControlPath ~/.ssh/master-%r@%h:%p
        ControlPersist 4h

It will keep your connection for 4 hours.

TIL - xxd color support

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

Today (2 January 2024), version 9.1 of the Vim editor has been released [1]!

xxd [2] is a utility that is distributed with Vim and is my go-to-tool when it comes to view or manipulating binary files.

A feature I've been missing for a long time is finally here - color support!

To enable colors, use the -R flag (same as for less and hexdump). E.g.:

$xxd -R always $FILE | less -R

The hex-value and value are both colored with the same color depending on the hex-value:

• 0x00 = white
• 0xff = blue
• printable = green
• non-printable = red
• tabs and linebreaks = yellow

TIL - git credential storage

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

When using SSH as transport protocol for connecting to remotes you could use a key without need to type a username nor password. Unfortunately, this is not possible when the underlaying protocol is HTTPS as it requires a username and password for every connection made.

This is where git credential store gets a chance to shine.

$ git config credential.helper store

[credential]
        helper = store

$ git config credential.helper 'store --file ~/.my-secrets'

TIL - Docker scratch image

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

The scratch image is the smallest possible image for docker. It does not contain any libraries nor other executables. It is simply a new, fresh and empty setup of namespaces.

The FROM scratch line is even a no-op [1] in the Dockerfile, which results in that it will not create an extra layer in you image. Example of a Dockerfile:

FROM scratch
ADD hello /
CMD ["/hello"]

As the Docker image does not contains any libraries, the hello application in the example above has to be compiled statically.

One use I see is to setup a Docker image based on a completely custom made root filesystem, e.g. the output from Buildroot.

See Docker documentation [2] for further reading.

TIL - Sort in VIM

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

After 15+ years of daily VIM usage I just discovered the :sort function. Quite embarassing.

It is also possible to sort in revese ( :sort!) and remove duplicate lines ( :sort u).

TIL - notmuch-lore

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

Notmuch [1] is an mail indexer and is a great tool to search in high-volume mailboxes (e.g. mailing lists). Being subscribed to all these mailing lists and retreiving all mails over IMAP daily could be quite annoying and harm your mail quota.

Therefor, public-inbox [2] makes archives of many of the public maling lists out there and makes it available in a git repository.

That is good, but you want to read your emails in your email-client, right?

TIL - git man-pages

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

I'm a big user of man-pages.

Today I found a set of pages that I've not noticed before when I was reading man git:

SEE ALSO
        gittutorial(7), gittutorial-2(7), giteveryday(7), gitcvs-migration(7), gitglossary(7), gitcore-tutorial(7),
       gitcli(7), The Git User’s Manual[1], gitworkflows(7)

Especially

• man gitcore-tutorial
• man giteveryday
• man gitglossary
• man gittutorial
• man gitworkflows

They are worth a look.

TIL - Git --color-moved

TIL, Today I Learned, is more of a "I just figured this out: here are my notes, you may find them useful too" rather than a full blog post

Did you know that Git is able to detect moved blocks and use different colors from the usual added/removed lines? Me neither until now.

The paremeter is --color-moved and has been around since v0.4.0, so there is no new feature.

This is from the git manual page [1] :

--color-moved[=<mode>]
Moved lines of code are colored differently. The <mode> defaults to no if the option is not given and to zebra if the option with no mode is given. The mode must be one of:

no
Moved lines are not highlighted.

default
Is a synonym for zebra. This may change to a more sensible mode in the future.

plain
Any line that is added in one location and was removed in another location will be colored with color.diff.newMoved. Similarly color.diff.oldMoved will be used for removed lines that are added somewhere else in the diff. This mode picks up any moved line, but it is not very useful in a review to determine if a block of code was moved without permutation.

blocks
Blocks of moved text of at least 20 alphanumeric characters are detected greedily. The detected blocks are painted using either the color.diff.{old,new}Moved color. Adjacent blocks cannot be told apart.

zebra
Blocks of moved text are detected as in blocks mode. The blocks are painted using either the color.diff.{old,new}Moved color or color.diff.{old,new}MovedAlternative. The change between the two colors indicates that a new block was detected.

dimmed-zebra
Similar to zebra, but additional dimming of uninteresting parts of moved code is performed. The bordering lines of two adjacent blocks are considered interesting, the rest is uninteresting. dimmed_zebra is a deprecated synonym.

The --color-moved argument can be used for any commands that generates a diff, such as git diff, git log -p, git stash show and more.

Example

This is an example of git diff where I have moved a function and made som small changes:

That the block is moved is clear, but it is not obvious what have changed in the block itself.

If we instead use --color-moved, we get a different style on the output:

The magenta and cyan is the moved block, and in addition, we get the red/green colors for removed/added lines.

$git config --global diff.colormoved default