Curl Flags Example — The Options You Actually Use

The command

curl -sS -L -f -H "Accept: application/json" -o out.json https://httpbin.org/json

What the flags do

Flag	What it does
`-X, --request`	Set the method. Rarely needed: `-d`, `-I` and `-T` already choose one.
`-H, --header`	Add, replace or remove a request header.
`-d, --data`	Send a body (form-encoded by default). Makes the request a POST.
`--json`	Send a JSON body with the JSON headers set (7.82+).
`-F, --form`	Send a multipart form field or file.
`-G, --get`	Put `-d` data in the query string of a GET.
`-u, --user`	Basic-auth credentials.
`-A, --user-agent`	Set the User-Agent header.
`-b, --cookie`	Send cookies, or read them from a file.
`-c, --cookie-jar`	Save received cookies to a file.
`-i, --include`	Print response headers before the body.
`-I, --head`	Send HEAD; print headers only.
`-v, --verbose`	Show the connection, the request and the response headers.
`-s, --silent`	No progress meter or error messages.
`-S, --show-error`	With `-s`, still print errors.
`-w, --write-out`	Print variables such as `%{http_code}` after the transfer.
`-o, --output`	Write the body to a named file.
`-O, --remote-name`	Write the body to a file named after the URL.
`-L, --location`	Follow redirects.
`-f, --fail`	Exit non-zero on HTTP 4xx and 5xx.
`-m, --max-time`	Overall time limit in seconds.
`--connect-timeout`	Time limit for establishing the connection.
`--retry`	Retry transient failures.
`-x, --proxy`	Send the request through a proxy.
`-k, --insecure`	Skip TLS certificate verification. Avoid.
`--compressed`	Ask for and decode compressed responses.
`-K, --config`	Read options from a file.

How flags combine

Single-letter flags that take no argument can be stacked behind one dash, so -sSL is -s -S -L. A flag that takes a value must come last in such a group, with its value after it: -sSLo file. Flags and the URL can appear in any order. A boolean long option can be switched off again by prefixing no-, as in --no-progress-meter, which is useful for overriding something set in a config file.

Case matters and the pairs are not related: -o and -O, -i and -I, -s and -S, -x and -X, -k and -K, -f and -F all do different things.

curl -sSLf -o page.html https://example.com/
curl -sS -w "%{http_code} %{time_total}s\n" -o /dev/null https://example.com/

A sensible default set for scripts

Interactive use and scripts want different behaviour. In a script, hide the progress meter but keep errors (-sS), treat HTTP errors as failures (-f), follow redirects if the URL may move (-L), and never wait forever (--max-time). Put options you always want in ~/.curlrc, one per line without the leading dashes, and bypass that file for a single command with -q as the first argument.

curl -fsSL --connect-timeout 5 --max-time 30 --retry 3 https://example.com/install.sh -o install.sh

Common mistakes

-X does not add a body or change behaviour; it only rewrites the method word. -X POST without data is an empty POST.
-s alone hides error messages too. Always pair it with -S.
Options differ between versions. Run curl --version, and curl --help all for the list your build supports.

Related curl examples

How to Use Curl

Curl is a command-line program that makes network requests and prints what comes back.

Curl -d Flag Example

-d looks like "send this data", but it does three things at once and quietly edits file input.

Curl Send Header Example

-H adds a header line to the request.

Curl Timeout Example

By default curl puts no limit on how long a transfer may take, so one silent server can hang a script indefinitely.

All Curl Examples

49 worked examples, grouped by what you are trying to do.

More under Reference

References

curl man page — Every option, with the version it was added in.
curl: options and versions — A table of which release introduced each command-line option.

These links leave api-tester.com, which is independent of the projects they point to.

FAQ

What are the most common curl flags?

-X for the method, -H for headers, -d for a request body, -i or -v to see headers, -o or -O to save output, -L to follow redirects, -u for credentials and -s to silence the progress meter.

Can I combine curl flags?

Yes. Single-letter flags without arguments can be written together, for example -sSL. A flag that takes a value must be last in the group.

How do I see all curl options?

Run curl --help all for the complete list, or man curl for the manual with a description of each option.