QR codes in a shell script

The network route: curl

The keyless API needs no key, no auth header and no install beyond curl itself:

curl -o qr.png "https://useqr.app/q/hello.png"

# with options, always url-encode the payload
curl -sG -o qr.png "https://useqr.app/api/v1/qr" \
  --data-urlencode "data=https://example.com/sale?src=poster" \
  --data "size=1024" --data "ec=Q"

The -G --data-urlencode pair matters: an unencoded & in your payload becomes a second query parameter and silently truncates the code's contents. More curl patterns live on the curl page.

The offline route: qrencode

qrencode is the classic CLI front-end to libqrencode, packaged everywhere (apt install qrencode, brew install qrencode). It runs with no network at all, which is the right choice when the payload is a WiFi password or anything else you should not send to a server:

qrencode -o qr.png -s 10 -m 4 -l M "https://example.com"
qrencode -t SVG -o qr.svg "https://example.com"

-s 10 is pixels per module, -m 4 is the 4-module quiet zone, -l M the error-correction level.

A QR code in your terminal

qrencode's party trick: render the code as text, no image file involved:

qrencode -t ANSIUTF8 "https://example.com"

This prints a scannable code using block characters directly in the terminal. It is genuinely useful: SSH into a server, generate a code for a URL sitting in a variable, and scan it off the terminal window with your phone, no file transfer step.

Batch: loop over a CSV

Given urls.csv with slug,url per line:

mkdir -p codes
while IFS=, read -r slug url; do
  curl -sG -o "codes/${slug}.png" "https://useqr.app/api/v1/qr" \
    --data-urlencode "data=${url}" --data "size=1024"
done < urls.csv

For hundreds of items, POST /api/v1/qr/batch accepts up to 100 items per call and is far fewer round trips: see bulk generation.

Verify in CI

A script that generates codes should also prove they decode. The verify endpoint renders, rasterises and reads the code back with a real decoder, and returns scannable in its JSON report:

url="https://example.com/download"
curl -sG "https://useqr.app/api/v1/verify" --data-urlencode "data=${url}" \
  | jq -e '.scannable' > /dev/null || { echo "QR failed to decode"; exit 1; }

jq -e sets the exit code from the value, so a non-scannable code fails the pipeline step. This is the whole decode-verify loop in two lines, and it belongs in any pipeline that puts codes in front of users, more patterns in QR codes in CI.

Which route when

Situation	Use
Public URL, no install allowed	curl + API
Credential or private payload	qrencode (offline)
Quick code to scan off a terminal	qrencode -t ANSIUTF8
Hundreds of codes	POST /api/v1/qr/batch
Print output	SVG from either route

FAQ

How do I generate a QR code in a bash script?

curl the keyless endpoint and write the bytes to a file, or install qrencode and run it offline. Both are one line; neither needs an API key.

How do I display a QR code in the terminal?

qrencode -t ANSIUTF8 "your text" prints a scannable code as block characters. It works over SSH and needs no image viewer.

How do I make QR codes for every row of a CSV?

Loop with while IFS=, read and call curl per row, or send up to 100 items at once to POST /api/v1/qr/batch to cut the round trips.

Can a script check that a code actually scans?

Yes. GET /api/v1/verify renders and decodes the code server-side and reports scannable true or false; pipe it through jq -e to fail a CI step automatically.