Generate QR codes quickly in linux terminal

Date: Aug 04, 2022
Author: Adeepa Gunathilake

Recently I had to type a long password to an app, but it’s super complex that typing is a headache. Password was in my password manager on laptop I decided to transfer the password using QR codes and then copy it.

Generating a QR is nothing hard these days, tons of online services for this now, but the thing is, my data is sensitive. Online services are not an option.

I searched how to generate QR codes from terminal and found this cool app called “qrencode”. It should be on every major distro repository.

Most common syntax is this.

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qrencode -l L -s 6 -o output.png 'Hello, world!'

-o option let you set the output and it is a required parameter. You can output to standard output by giving -o the value -. The -l option is the error correction level. Possible values are L, M Q, H and L is the lowest, H is the heighest. M is medium, Q is higher than medium but lower than H. -s is the pixel size. Default is 3 but I prefer 6. Having pixel size 6 will generate large QR.

Typing that command each time and opening the image is hard work. Let’s simplify the process. I wrote a shell function for this.

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function generate-qr {
    rand_file_name=$(mktemp -t qrgen.XXXXXX);
    qrencode -s 6 -l H -o "$rand_file_name" "$1";
    sxiv -p "$rand_file_name";
    rm -f "$rand_file_name";
    unset rand_file_name;
}

The mktemp command will create a temporary file in the OS specific temporary directory. In our case /tmp. If that command is not available, search your distro repos. It should be there. Then we output the qr in png form to that temporary file and display it in sxiv so the mobile phone can read it. When we close sxiv our qr png will also get deleted.

Now generating QR codes are as easy as this.

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generate-qr "Hello world"

That’s it.

Don’t be skid. Peace.