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1834 posts latest post 2026-04-18
Publishing rhythm
Apr 2026 | 20 posts
Bash mktemp

There is GNU coreutils command called mktemp that is super handy in shell scripts to make temporary landing spots for files so that they never clash with another instance, and will automatically get cleaned up when you restart, or whenever /tmp gets wiped. I’m not sure when that is, but I don’t expect it to be long.

Here are some examples of making temp directories in different places, my favorite is mktemp -dt mytemp-XXXXXX.

# makes a temporary directory in /tmp/ with the defaul template tmp.XXXXXXXXXX mktemp # makes a temporary directory in your current directory mktemp --directory mytemp-XXXXXX # shorter version mktemp -d mytemp-XXXXXX # same thing, but makes a file mktemp mytemp-XXXXXX # makes a temporary directory in your /tmp/ directory (or what ever you have configured as your TMPDIR) mktemp --directory --tmpdir mytemp-XXXXXX # shorter version mktemp -dt mytemp-XXXXXX # same thing, but makes a file mktemp --tmpdir mytemp-XXXXXX # shorter version mktemp -t mytemp-XXXXXX

Use Case #

Here is a sample script that shows how to capture the tempdir as...

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Recover a lost git branch with checkout

Once you give a branch the big D (git branch -D mybranch) its gone, its lost from your history. It’s completely removed from your log. There will be no reference to these commits, or will there?

Checkout is your savior, all you need is the commit hash.

your terminal is still open

We have all done this, you give branch the big D only to realize it was the wrong one. Don’t worry, not all is lost, this is the easiest to recover from. When you run the delete command you will see something like this.

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git find deleted files

It’s nearly impossible to completely loose a file if it is commited to git. It’s likely harder to fully remove the file than it is to recover it, but how do we go about recovering those precious files that we have lost.

Listing all the deleted files in all of git history can be done by combining git log with --diff-filter. The log gives you lots of options to show different bits of information about the commit that happened at that point. It’s even possible to get a completely clean list of files that are in your git history but have been deleted.

These various commands will show all files that were ever deleted on your current branch.

# This one includes the date, commit hash, and Author git log --diff-filter D # this one could be a git alias, but includes empty lines git log --diff-filter D --pretty="format:" --name-only # this one has the empty lines cleaned up git log --diff-filter D --pretty="format:" --name-only...

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git
git diff-filter

Git commands such as diff, log, whatchanged all take a flag called --diff-filter. This can filter for only certain types of diffs, such as added (A), modified (M), or deleted (D).

You can find the full description by searching for --diff-filter in the man git diff page.

--diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]] Select only files that are Added (A), Copied (C), Deleted (D), Modified (M), Renamed (R), have their type (i.e. regular file, symlink, submodule, ...) changed (T), are Unmerged (U), are Unknown (X), or have had their pairing Broken (B). Any combination of the filter characters (including none) can be used. When * (All-or-none) is added to the combination, all paths are selected if there is any file that matches other criteria in the comparison; if there is no file that matches other criteria, nothing is selected. Also, these upper-case letters can be downcased to exclude. E.g....

git
Textual Popup Hack

As I am toying around with textual, I am wanting some popup user input to take over. Textual is still pretty new and likely to change quite significantly, so I don’t want to overdo the work I put into it, So for now on my personal tuis I am going to shell out to tmux.

The main issue is that when you are in a textual app, it kinda owns the input. So if you try to run another python function that calls for input it just cant get there. There is a textual-inputs library that covers this, and it might work really well for some use cases, but many of my use cases have been for things that are pre-built like copier, and I am trying to throw something together quick.

textual is still very beta

Part of this comes down to the fact that textual is still very beta and likely to change a lot, so all of the work I have done with it is for quick and dirty, or fun side projects.

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Install obs flatpak

Big announcement recently that obs studio now builds out to a flatpak, hopefully making it easier for all of us to install, especially us near normies that don’t regularly compile anything from source.

I did not have flatpak installed so the first thing I had to do was get the flatpak command installed, and add their default repo.

sudo apt install flatpak flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo

Once I had flatpak, I was able to get obs installed with the following command.

flatpak install flathub com.obsproject.Studio

Once Installed it fired right up for me with the next command they suggested.

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GitHub Markdown now Supports Mermaid Diagrams

Mermaid diagrams provide a way to display graphs defined as plain text. Some markdown renderers support this as a plugin. GitHub now supports it.

You can define nodes like this in mermaid, and GitHub will now render them as a pretty graph diagram. Its rendered in svg, so its searchable with control f and everything.

graph TD; A-->B; A-->C; B-->D; C-->D-->OUT; E-->F-->G-->OUT

Here is what the example looks like on GitHub

Git rebase to the beginning of time

Git has a built in way to rebase all the way back to the beginning of time. There is no need to scroll through the log to find the first hash, or find the total number of commits. Just use --root.

Glances can watch docker processes

Glances is a system monitor with a ton of features, including docker processes.

I have started using portainer to look at running docker processes, its a great heavy-weight docker process monitor. glances works as a great lightweight monitor to just give you the essentials, ( Name, Status, CPU%, MEM, /MAX, IOR/s, IOW/s, Rx/s, Tx/s, Command)

You will need to install glances to use the glances webui. We can still use pipx to manage our virtual environment for us so that we do not need to do so manually or run the risk of globally installed package dependency hell.

pipx install glances pipx inject glances "glances[docker]"

You will be presented with this success message.

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Revive files from the dead with git

Git reflog can perform some serious magic in reviving your hard work from the dead if you happen to loose it.

You must git commit! If you never commit the file, git cannot help you. You might look into your trashcan, filesystem versions, onedrive, box, dropbox. If you have none of this, then you are probably hosed.

I really like to practice these techniques before I need to use them so that I understand how they work in a low stakes fashion. This helps me understand what I can and cannot do, and how to do it in a place that does not matter in any way at all.

This is what I did to revive a dropped docker-compose.yml file. The idea is that if I can find the commit hash, I can cherry-pick it.

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Glances webui with pipx

Glances has a pretty incredible webui to view system processes and information like htop, or task manager for windows.

The nice thing about the webui is that it can be accessed from a remote system. This would be super nice on something like a raspberry pi, or a vm running in the cloud. Its also less intimidating and easier to search if you are not a terminal junky.

You will need to install glances to use the glances webui. We can still use pipx to manage our virtual environment for us so that we do not need to do so manually or run the risk of globally installed package dependency hell.

pipx install glances pipx inject glances "glances[web]"

You will be presented with this success message.

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Git reflog is an alias for git log -g

Right inside the git docs, is states that the git reflog command runs git reflog show by default which is an alias for git log -g --abbrev-commit --pretty=oneline

This epiphany deepens my understanding of git, and lets me understand that most git log flags might also work with git log -g.

Here are some git commands for you to try out on your own that are all pretty similar, but vary in how much information they show.

# These show only first line of the commit message subject, the hash, and index git reflog git log -g --abbrev-commit --pretty=oneline # similar to git log, this is a fully featured log with author, date, and full # commit...

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Run glances without install with pipx

Glances is a fully featured system monitoring tool written in python. Out of the box it’s quite similar to htop, but has quite a few more features, and can be ran without installing anything other than pipx, which you should already have installed if you do anything with python.

pipx run glances

Once you run this you will be in a tui application similar to htop. You can kill processes with k, use left and right arrows to change the sorting column, and up and down to select different processes.

Nested requirements.txt in python

python requirements text files can in fact depend on each other due to the fact that you can pass pip install arguments right into your requirements.txt file. The trick is to just prefix the file with a -r flag, just like you would if you were installing it with pip install

Lets create two requirements files in a new directory to play with.

mkdir requirements-nest cd requirements-nest touch requirements.txt requirements_dev.txt

Then add the following to each requirements file.

# requirements.txt kedro[pandas.ParquetDataSet] 

# requirements_dev.txt -r requirements.txt ipython

Installing #

Installing requirements_dev.txt will install both ipython and pandas since it includes the base requirements file.

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Modded Minecraft in Docker

In my adventure to put more homelab in docker, I moved our modded minecraft setup to docker.

So far I have found all of our mods from curse forge. modpacks make getting multiple mods working together much easier, someone else has already vetted a pack of often times 100+ mods that all play well together. I have yet to get these working in docker, I will, but for not I just have individual mods.

under the hood docker is using wget to get the mod. The link you click on from curseforge will block wget. What I do is pop open the devtools (f12 in chrome), click on the network tab, click the download link on the web page, and watch the real link show up.

I am using docker compose, it makes the command much easier to start, and all...

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View AWS event bridge rules with visidata

Reading eventbridge rules from the command line can be a total drag, pipe it into visidata to make it a breeze.

I just love when I start thinking through how to parse a bunch of json at the command line, maybe building out my own custom cli, then the solution is as simple as piping it into visidata. Which is a fantastic tui application that had a ton of vim-like keybindings and data features.

Vim remaps use cmd in place of :

Anyone just starting out their vim customization journey is bound to run into this error.

E5520: <Cmd> mapping must end with <CR>

I did not get it #

I’ll admit, in hindsight it’s very clear what this is trying to tell me, but for whatever reason I still did not understand it and I just used a : everywhere.

If you run :h <cmd> you will see a lot of reasons why you should do it, from performance, to hygene, to ergonomics. You will also see another clear statement about how to use <cmd>.

E5520 <Cmd> commands must terminate, that is, they must be followed by <CR> in the {rhs} of the mapping definition. Command-line mode is never entered.

When to map with a : #

You still need to map your remaps with a : if you do not close it with a <cr>. This might be something like prefilling a command with a search term.

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