curl is normally used to issue a single request against a URL. Sometimes you need to issue multiple requests against a URL, or quickly stress test a server or endpoint. You don’t have to do this using bash’s loops, instead you can use curl’s own sequences feature, []
Here’s an example using httpbin:
curl -s "https://httpbin.org/anything?a=[0-5]"curl will issue 6 request, starting with ?a=0 to ?a=5, one after the other. You can see the querystring reflected in the response body.
{
...
"method": "GET",
"url": "https://httpbin.org/anything?a=0"
}
{
...
"method": "GET",
"url": "https://httpbin.org/anything?a=1"
}
...
The sequence can go anywhere in the URL and curl will increment it. The sequence can also be letters instead of numbers.
curl -s "https://httpbin.org/anything/file_[a-f].txt"It’s also possible to specify a step using :, regardless of letters or numbers.
curl -s "https://httpbin.org/anything/file_[a-f:3].txt"If you want to use items from a specific list, use {} with your comma separated values inside.
curl -s "https://httpbin.org/anything/{lorem,ipsum,dolor}"And finally you can mix and match sequences together.
curl -s "https://httpbin.org/anything/[0-6:3]_file_{lorem,ipsum,dolor}"