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.