Alexander Gromnitsky's Blog

Reddit instead of fortune(1)

Air Date: 2024-12-16
Latest update: 2024-12-17 18:18:23

The idea of fetching some Reddit post titles to print them randomly in the terminal dates back to at least 2016. Taking the feed from /r/showerthoughts subreddit, for example, one could place the following script into his .bash_login or elsewhere:

It's a slightly naïve 3-liner that tries to protect itself from 429 that Reddit frequently returns, in which case the script gracefully outputs nothing. w3m is required to convert & & friends into their corresponding symbols.

The 1st enhancement here would be to cache the JSON. The enterprise approach is to set up a cron job that saves the data into a temporary file &, if that operation succeeds, renames it into a well known (by the script that parses the JSON) path.

The mickey mouse way is to check the mtime of the previously saved JSON & delete the file once it becomes too old.

The 2nd enhancement would be to fetch multiple subreddits & merge them together.

A relatively small makefile can handle all this:

$ cat reddit-wisdom
#!/usr/bin/make -sf

r := showerthoughts CrazyIdeas oneliners
update := 600

wits := /tmp/reddit-wisdom/all.txt
age := $(shell expr `date +%s` - `date -r $(wits) +%s 2>/dev/null || echo 0`)
$(shell [ $(age) -gt $(update) ] && rm -f /tmp/reddit-wisdom/*)

all: $(wits)
    sort -R < $< | head -1 | w3m -dump -T text/html

$(wits): $(patsubst %, /tmp/reddit-wisdom/%.json, $(r))
    jq -r '.data?.children[]?.data | "\"\(.title)\" -- \(.author)" | gsub("\\n"; " ")' $^ > $@

/tmp/reddit-wisdom/%.json:
    mkdir -p $(dir $@)
    echo Fetching r/$*
    curl -sf 'https://www.reddit.com/r/$*/top.json?sort=top&t=week&limit=100' > $@

.DELETE_ON_ERROR:

It considers remote data stale if it's older that 600 seconds. I think it's safe to increase the value to at least 48 hours.

Note that the default subreddits might include NSFW content.

$ ./reddit-wisdom
Fetching r/showerthoughts
Fetching r/CrazyIdeas
Fetching r/oneliners
"The shovel was a ground breaking invention." -- EndersGame_Reviewer
$ ./reddit-wisdom
"Name your daughters Elle and Noelle" -- EmpireStrikes1st

Tags: ойті
Authors: ag

ESLint's flat config and Emacs

Air Date: 2024-09-07
Latest update: 2024-09-07 11:28:14

I expected to use this "new" eslint as follows:

have a user-wide eslint installation with a personal default configuration;
given #1, to be able to run eslint in any project (mine or not) to check it against my personal rules;
if a project has node_modules/.bin/eslint script (implying there is a config file in the project's root directory), running node_modules/.bin/eslint should ignore the global config and use the local one;
Flycheck in Emacs should automatically execute either node_modules/.bin/eslint (if it exists) or the global version otherwise.

Naïvely installing eslint via 'npm i -g' won't do much good since any plugins must still be installed locally.

Hence, I created a directory ~/lib/dotfiles/eslint solely for a "global", user-wide installation & configuration:

|-- eslint*
|-- eslint.config.mjs
|-- node_modules/
|   |-- .bin/
|   |   `-- eslint -> ../eslint/bin/eslint.js*
|   `-- eslint/
`-- package.json

where eslint is a shell script, symlinked from a directory in PATH:

$ stat -c%N `which eslint`
'/home/alex/bin/eslint' -> '/home/alex/lib/dotfiles/eslint/eslint'
$ cat eslint
#!/bin/sh

__dir__=$(dirname "$(readlink -f "$0")")
"$__dir__"/node_modules/.bin/eslint -c "$__dir__"/eslint.config.mjs "$@"

and eslint.config.mjs has common rules for .js files and files without extensions:

import globals from 'globals'
import js from '@eslint/js'
import react from 'eslint-plugin-react'

export default [
  js.configs.recommended,
  {
    rules: {
      "no-unused-vars": [ "warn", { "argsIgnorePattern": "^_" } ],
      …
    },
    languageOptions: {
      globals: {
        ...globals.browser,
        ...globals.node,
        …
      }
    }
  },
  {
    files: ["**/!(*.*)"],
    ignores: ["**/{Makefile,Rakefile,Gemfile,LICENSE,README}"],
  },
  …
]

If you don't care about any custom configurations that arrive with almost any JS project, you may stop here. Otherwise, we need to instruct Emacs where to search for eslint executable.

(defun my--npm-exec-path()
  (let ((npm-root (string-trim
                   (shell-command-to-string "npm root 2>/dev/null"))))
    (when (not (string= "" npm-root))
      (make-local-variable 'exec-path)
      (add-to-list 'exec-path (file-name-concat npm-root ".bin"))
      )))
(add-hook 'js-mode-hook 'my--npm-exec-path)
(add-hook 'js-mode-hook 'flycheck-mode)

This tells the editor to invoke my--npm-exec-path function every time Emacs opens a .js file. The function runs npm root to guess the proper path for node_modules directory and prepends Emacs' internal exec-path list with the path where the eslint script might be installed. Iff such a script is found by Flycheck, our global ~/lib/dotfiles/eslint/eslint.config.mjs is ignored.

Tags: ойті
Authors: ag

Visualising curl downloads

Air Date: 2024-07-11
Latest update: 2024-07-14 21:45:57

If downloading from a server is slow, how would you prove to a devops guy that you're experiencing a slowdown? There are a couple of possibilities, the worst of which would be sending a video. What if you send a speed graph using data from curl?

Every second curl prints to stderr the following:

fprintf(tool_stderr,
        "\r"
        "%-3s " /* percent downloaded */
        "%-3s " /* percent uploaded */
        "%s " /* Dled */
        "%s " /* Uled */
        "%5" CURL_FORMAT_CURL_OFF_T " " /* Xfers */
        "%5" CURL_FORMAT_CURL_OFF_T " " /* Live */
        " %s "  /* Total time */
        "%s "  /* Current time */
        "%s "  /* Time left */
        "%s "  /* Speed */
        "%5s" /* final newline */,
        …

Therefore, by replacing \r with \n we can send a download log:

$ curl http://example.com/1.zip -o 1.zip 2>&1 | tr \\r \\n

To draw a graph with gnuplot, we can use Current time and Speed columns. Gnuplot understands time as input data, but I don't know how to persuade it to interpret values like 100k or 200M, thus we need to convert them into 'bytes'. This is a cute little problem for code golf, but amusingly, it was already solved in coreutils > 12 years ago via numfmt(1).

$ echo 1M and 10M | numfmt --from iec --field 3
1M and 10485760

(macOS & FreeBSD both have coreutils package, where the utility executable is prefixed with 'g'.)

#!/usr/bin/env -S stdbuf -o0 bash

set -e -o pipefail
numfmt=`type -p gnumfmt numfmt;:`; test "${numfmt:?}"

cat <<E
set xdata time
set timefmt "%H:%M:%S"
set xlabel "Time, MM:SS or HH:MM:SS"
set format y "%.0s%cB"
set ylabel "Speed, Unit/second" offset -1,0
set grid
plot "-" using 1:2 with lines title ""
E

curl "$@" -fL -o /dev/null 2>&1 | tr \\r \\n | awk '
/[0-9.][kMGTP]?$/ {
  time = index($10, ":") == 0 ? $11 : $10
  if (time != "--:--:--") print time, $NF
}' | tr k K | $numfmt --from iec --field 2

Usage:

$ ./curlbench http://example.com/1.zip | gnuplot -p

Tags: ойті
Authors: ag

What's the use of 'use case'?

Reddit instead of fortune(1)

ESLint's flat config and Emacs

Visualising curl downloads