851 words

4 minutes

i3blocks Air Quality Module

2019-07-17

dev

i3blocks

/

curl

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sed

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awk

Hello!
This is post is old and possibly outdated. I’m keeping it here for reference. (2024/09/01)

Overview#

Making API requests then displaying response on i3bar. Using cURL,sed, and AWK to retrieve & manipulate the response data. This post will cover the process of making a module for i3blocks to display the local air quality index (AQI).

Why?#

During my stay in South Korea, I’ve noticed that air quality was a rising isse. The residents are mostly blaming it on the neighbouring country, but I’m not going to get into that.

Rather than fixing the bigger problem, I’ve decided to write a small module for my status bar to keep me updated on the local air quality. I’m doing little things that I can actually achieve.

It’s called a “module” but under the hood, they’re simply a group of commands to display a number on my status bar. Nothing new there. There are existing modules out there to show weather reports, and I knew where to get the AQI from, so all I had to do was simply put the two together.

Preparation#

First I needed to grab the air quality data from somewhere, then I came across this website. By default, it shows your location, local air quality forecast, and explains what the numbers mean.

Further down the page, there’s a link to their API, which returns more information than I needed, so I still needed to put in some effor to make the information usable for the status bar.

I needed to get a token to access the API, which was well documented on the initial setup section of the page. Once I got my token, I was able to make a successful request using cURL:

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curl -s http://api.wapi.info/feed/here/?token=yourtoken

which returns following format:

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{
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    "status":"ok",
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    "data":
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    {
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        "aqi":69,
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        "idx":xxxx,
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        "attributions":
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        [
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            {
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                "url":"https://www.airkorea.or.kr/",
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                "name":"South Air Korea Environment Corporation"
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            },
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            {
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                "url":"https://waqi.info/",
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                "name":"World Air Quality Index Project"
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            }
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        ],
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        "city":
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        {
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            "geo":[latitude,longitude],
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            "name":"Some City, Some Place, Somewhere, South Korea",
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            "url":"https://aqicn.org/city/korea/some/place"
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        },
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        "time":
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        {
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            "s":"2019-07-10 22:00:00",
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            "tz":"+09:00",
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            "v":1562796000
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        },
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        "debug":
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        {
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            "sync":"2019-07-10T22:26:57+09:00"
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        }
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    }
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}

Pretty standard JSON response. Using here returns the local air quality, the website also contains a list of all available cities.

Now What?#

I saved the response to a file, which was done with pipes and redirection.

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curl -s http://api.wapi.info/feed/here?token=mytoken > ~/file/location/airdata

Now with a file to work with, I had to trim the response because I only needed to AQI value.

I decided to use sed and awk for this text manipulation, there’s a better way to do this probably, but this is how I did it.

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sed "s/,/\n/g;s/:/ /g" ~/file/location/airdata | awk /data/ | awk "{print \$3}"

Breakdown#

sed is a stream editior, it reads the file line by line and performs the operations that are given.
- s/,/\n/g replaces all the commas with new line character \n.
- s/:/ /g replaces all the colons with spaces.
awk /data/ prints the line that contains the word “data”.
awk "{print \$3}" prints the third word of the line.

Output for each command:

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{"status" "ok" "data" {"aqi" 69
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"data" {"aqi" 69
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69

Nice, now that I have what I need, I can move on to the i3blocks part of this.

Some Assembly Required#

Luke Smith’s weather module for LARBS was a good place to start.

I had to modify the script to point to the correct directoy and file, which will be created by the script later.

rm -f "$HOME/.local/share/airdata" ;}

This will clear pre-existing data file when the script runs.

I modified the getforecast() function into get_air_quality().

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get_air_quality() {
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    ping -q -c 1 1.1.1.1 > /dev/null || exit 1
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    curl -s "http://api.wapi.info/feed/here?token=mytoken" > "$HOME/.local/share/airdata" || exit 1
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}

This will:

Check if device is connected to the internet.
Then send a request to the API.
Save the response into a file called airdata.

Which will be read by the script. Then I modified the showforecast() function into show_air_quality().

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show_air_quality() {
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    sed "s/,/\n/g;s/:/ /g" $HOME/.local/share/airdata | awk /data/ | awk "{print \"AQI: \" \$3}"
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}

This function will return something that looks like AQI: 69, which will be displayed on the status bar.

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case $BLOCK_BUTTON in
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    2) get_air_quality && show_air_quailty ;;
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    3) pgrep -x dunst >/dev/null && notify-send "Air Quality Module" "\- Middle click to update forecast.
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-AQI - Air Quality Index
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   0-50: Good
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 51-100: Moderate
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101-150: Mildly Unhealthy
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151-200: Unhealthy" ;;
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esac
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if [ "$(stat -c %y "$HOME/.local/share/airdata" >/dev/null 2>&1 | awk '{print $1}')" != "$(date '+%Y-%m-%d')" ]
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  then rm $HOME/.local/share/airdata && get_air_quality && show_air_quality
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  else show_air_quality
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fi

Mouse Actions
Each case corresponds to different mouse actions:

1) Left click

2) Middle click

3) Right click

For this module, I’ve yet to find a use for left clicking on the module, so I decided to leave it out. I added some descriptions for the numbers. Saved the file as “airquality”, then added it to my i3blocks config gile, then set it to update every 30 minutes.

Final Touches#

Still need to make the script executable. chmod +x ~/.local/bin/statusbar/airquality in my case.

Wrapping Up#

Once I reloaded the i3wm, I was agreeted with an air quality index. The module responds to mouse actions as expected, and I’m happy with the result.

Writing this module was a good practice, since I got to write something that I found useful, and it was pretty easy to do so since most of the work was already done for me. I got to make something I could use everyday.