Goal

To provide an open-source alternative to the Docker image escalope/pandoc-mermaid-plantuml, whose Dockerfile isn’t available.

The rationale behind these difficult setup is simple: construct informative Mermaid diagram with intuitive Markdown syntax in an open-source and economic way.

This newly constructed Docker image is entirely on GitLab. No Docker Hub account is needed. For sample usage, consult .gitlab-ci.yml in my test project.

Difficulties

1. issues raghur/mermaid-filter#51 and #52
2. issue gitlab-org/gitlab-runner#4566

Useful code/articles

1. time-machine-project/requests-for-comments@470b0c5 Dockerfile
2. Reduce Docker Image Sizes Using Alpine
3. Best practices for building docker images with GitLab CI with the accompanying gist
4. The code block in the highlighted comment in item 2 of the above section
5. pandoc installation for Docker
6. Sample Dockerfile for Alpine Linux in the troubleshooting of Puppeteer
7. sc250024/docker-mermaid-cli@3c9ddb5 src/puppeteerConfigFile.json
8. raghur/mermaid-filter project README’s section about Puppeteer config file

When one changes connection type (say, from ethernet to Wi-Fi), the interface name changes (e.g. eth0 → wlan1). To avoid changing Conky config file all the time, here’s a little Lua function for finding the network interface name.

function findInterface()
    local handle = io.popen('ip a | grep "state UP" | cut -d: -f2 | tr -d " "')
    local result = handle:read('*a'):gsub('\n$','')
    handle:close()
    return result
end

1. ip a gives everything about connection info. Each entry looks like

    3: wlp3s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
   

2. Grep the “state UP” and extract the second field, using : as a delimiter. Trim off the spaces around.

   [Read More]

Background

I’m using Conky for monitoring the system. After a system upgrade, the CPU temperatures were gone. Conky’s standard error showed the following.

Conky: can't open '/sys/class/hwmon/hwmon0/temp3_input': No such file or
directory please check your device or remove this var from Conky...

Source of message: https://bbs.archlinux.org/viewtopic.php?id=82231

An easy fix would be to adjust the following lines in .conkyrc according to the number N in /sys/class/hwmon/hwmonN containing the file temp3_input. (You may adjust the number 3 according to the number of CPU of your device.) The number of CPU can be found using grep -c ^processor /proc/cpuinfo.

Background

I’ve to take screenshots to demonstrate Conky’s visual output.

I’ve chosen Byzanz after reading this answer on Ask Ubuntu.

Peek is more user-friendly, but I prefer CLI’s precision. That’s feasible thanks to a comment mentioning xwininfo.

After typing xwininfo, click on the target window. Switching to adjacent workplace is possible.

$ xwininfo
xwininfo: Please select the window about which you
          would like information by clicking the
          mouse in that window.

xwininfo: Window id: 0x1c0000a "Desktop"

  Absolute upper-left X:  0
  Absolute upper-left Y:  0
  Relative upper-left X:  0
  Relative upper-left Y:  0
  Width: 1920
  Height: 1080
  Depth: 32
  Visual: 0x1a7
  Visual Class: TrueColor
  Border width: 0
  Class: InputOutput
  Colormap: 0x1c00009 (not installed)
  Bit Gravity State: NorthWestGravity
  Window Gravity State: NorthWestGravity
  Backing Store State: NotUseful
  Save Under State: no
  Map State: IsViewable
  Override Redirect State: no
  Corners:  +0+0  -0+0  -0-0  +0-0
  -geometry 1920x1080+0+0

The --x and --y parameters below correspond to the absolute upper-left position of the window.

Background

Updated $\LaTeX$ version

From this $\TeX$-SE question about tlmgr, we see some advantages of installing $\TeX$Live directly from the official site:

1. avoid errors due to outdated version of $\TeX$Live supplied by the OS’s package manager
2. easier to manage packages with tlmgr.
3. enjoy the newer version of $\TeX$Live not yet available in your current GNU/Linux version.

The installation took about 30 minutes and 5G in the disk. I’ve chosen a local installation as this didn’t require sudo privileges. The whole process went smooth and the system displayed a message about setting

Update: Thanks to JuliaRegistries/General#647, the version cap of the package Distributions has now been removed, so that one can directly install the package GLM along with Distributions v0.19.2.

Background

I’m reading the book Statistics with Julia, which makes use of GLM.

Problem

I encountered the following error, which I posted in the issue GLM.jl#311.

(v1.1) pkg> add GLM
 Resolving package versions...
ERROR: Unsatisfiable requirements detected for package GLM [38e38edf]:
 GLM [38e38edf] log:
 ├─possible versions are: [0.2.0-0.2.5, 0.3.0-0.3.2, 0.4.0-0.4.8, 0.5.0-0.5.6, 0
.6.0-0.6.1, 0.7.0, 0.8.0-0.8.1, 0.9.0, 0.10.0-0.10.1, 0.11.0, 1.0.0-1.0.2, 1.1.0
-1.1.1] or uninstalled
 ├─restricted to versions * by an explicit requirement, leaving only versions [0
.2.0-0.2.5, 0.3.0-0.3.2, 0.4.0-0.4.8, 0.5.0-0.5.6, 0.6.0-0.6.1, 0.7.0, 0.8.0-0.8
.1, 0.9.0, 0.10.0-0.10.1, 0.11.0, 1.0.0-1.0.2, 1.1.0-1.1.1]
 ├─restricted by compatibility requirements with DataFrames [a93c6f00] to versio
ns: [0.4.0-0.4.8, 0.5.0-0.5.6, 0.6.0-0.6.1, 0.7.0, 0.8.0-0.8.1, 0.9.0, 0.10.0-0.
10.1, 0.11.0, 1.0.0-1.0.2, 1.1.0-1.1.1] or uninstalled, leaving only versions: [
0.4.0-0.4.8, 0.5.0-0.5.6, 0.6.0-0.6.1, 0.7.0, 0.8.0-0.8.1, 0.9.0, 0.10.0-0.10.1,
 0.11.0, 1.0.0-1.0.2, 1.1.0-1.1.1]
 │ └─DataFrames [a93c6f00] log:
 │   ├─possible versions are: [0.1.0, 0.2.0-0.2.5, 0.3.0-0.3.16, 0.4.0-0.4.3, 0.
5.0-0.5.12, 0.6.0-0.6.11, 0.7.0-0.7.8, 0.8.0-0.8.5, 0.9.0-0.9.1, 0.10.0-0.10.1, 
0.11.0-0.11.7, 0.12.0, 0.13.0-0.13.1, 0.14.0-0.14.1, 0.15.0-0.15.2, 0.16.0, 0.17
.0-0.17.1, 0.18.0-0.18.2] or uninstalled
 │   └─restricted to versions 0.18.2 by an explicit requirement, leaving only ve
rsions 0.18.2
 ├─restricted by compatibility requirements with StatsBase [2913bbd2] to version
s: [0.11.0, 1.0.0-1.0.2, 1.1.0-1.1.1] or uninstalled, leaving only versions: [0.
11.0, 1.0.0-1.0.2, 1.1.0-1.1.1]
 │ └─StatsBase [2913bbd2] log:
 │   ├─possible versions are: [0.1.0, 0.2.0-0.2.1, 0.2.3-0.2.10, 0.3.0-0.3.13, 0
.4.0-0.4.4, 0.5.0-0.5.3, 0.6.0-0.6.16, 0.7.0-0.7.4, 0.8.0-0.8.3, 0.9.0, 0.10.0, 
0.11.0-0.11.1, 0.12.0, 0.13.0-0.13.1, 0.14.0-0.14.1, 0.15.0, 0.16.0-0.16.1, 0.17
.0, 0.18.0, 0.19.0-0.19.5, 0.20.0-0.20.1, 0.22.0, 0.23.0-0.23.1, 0.24.0, 0.25.0,
 0.26.0, 0.27.0, 0.28.0-0.28.1, 0.29.0, 0.30.0] or uninstalled
 │   └─restricted to versions 0.30.0 by an explicit requirement, leaving only ve
rsions 0.30.0
 └─restricted by compatibility requirements with Distributions [31c24e10] to ver
sions: uninstalled — no versions left
   └─Distributions [31c24e10] log:
     ├─possible versions are: [0.1.0-0.1.4, 0.2.0-0.2.13, 0.3.0, 0.6.4-0.6.7, 0.
7.0-0.7.6, 0.8.0-0.8.10, 0.9.0, 0.10.0-0.10.2, 0.11.0-0.11.1, 0.12.0-0.12.5, 0.1
3.0, 0.14.0-0.14.2, 0.15.0, 0.16.0-0.16.4, 0.17.0, 0.18.0, 0.19.1-0.19.2] or uni
nstalled
     └─restricted to versions 0.19.2 by an explicit requirement, leaving only ve
rsions 0.19.2

Discussion

Although the packages StatsBase and DataFrames appear in the above error message, the cause of this problem was actually the package Distributions.

Problem

The touchpad on my new Ubuntu 18.04 LTS laptop was frozen. Toogling 🖱 with <Fn>-<F4> didn’t worked.

Attempt

1. Logout: didn’t work at all
2. Reboot: worked most of the time

Partial solution

After changing the Mouse Click Emulation in Keyboard & Mouse in Ubuntu Tweak from the default “Fingers” (2 fingers for right click; 3 fingers for middle click) to “Area” (Right/middle click determined by clicked area), one might have to wait for next reboot.

Goal

To install Juno for convenient development in Julia.

Problem

After Juno installation, I received the following error.

Analysis

From the error message, the system had tried to find an executable file julia, which would then be executed by the shell /bin/sh. Nonetheless, it’s absent from the system’s environment $PATH, so Juno couldn’t find it.

I’ve only changed my $PATH in ZSHRC, which is user-specific.

Solution

This Stack Overflow question about $PATH setting on *nix has provided various solution. As I was in a hurry to get Julia run on Juno, I’ve taken the advice from the best answer. I prefer creating a separate shortcut under /usr/bin, rather than editing system-wide config files.

Problem

During the adoption of Mmark for math posts on this blog, I had to insert markup: mmark at the last line of front matter of the source file of each math post.

Seek help

I separated this into two SO questions

1. Sed conditional match and execute command with offset, and
2. A question about AWK multiple line recognition.

Solution

From #1., I learnt the use of variables in AWK scripts. From #2, some users explained how these variables can be used for multi-line regex search.

Goal

To create a copy button for my Math.SE comment template in order to save the trouble of copying and pasting.

My first attempt

I put the boilerplate inside a Markdown codeblock to prevent them from getting interpreted by Hugo’s Markdown parser. Under each codeblock, I placed the copy button.

Comment boilerplate goes here ...

📝

Another comment boilerplate goes here ...

📝

…

My page’s original layout

$(document).ready(function() {
  $('.copyBtn').click(function() {
    copy($(this).prev().children())
j  });
});

function copy(selector) {
  var screenTop = $(document).scrollTop();
  var $temp = $("<div>");
  $("body").append($temp);
  $temp.attr("contenteditable", true)
       .html($(selector).html()).select()
       .on("focus", function() { document.execCommand('selectAll',false,null) })
       .focus();
  document.execCommand("copy");
  $temp.remove();
  $('html, body').scrollTop(screenTop);
}

static/js/copyBtn.js at Git tag copyBtn0