curl，用于发送请求的命令行工具，一个 HTTP 请求客户端（实际上它也可以做 FTP/SCP/TELNET 协议的事情，可类比于浏览器中的 fetch。
curl 是最为流行的 HTTP 请求命令行工具，在谷歌浏览器控制台的网络面板中，可将当前请求转化为 curl。
在学习及调试 HTTP 的过程中，可结合 curl 与 Apifo Echo 一同使用。
Apifox Echo 是 Apifox 出品的一款 HTTP 简单的接口请求和返回数据服务，可以模拟各种接口请求参数和返回数据的情况，供开发人员和测试人员学习测试 API 使用。
直接发送 GET 请求：
$ curl ifconfig.me 118.73.227.215
--request/-X，指定请求方法，如 POST 等。
$ curl \
-X POST \
-H "Accept: application/vnd.github+json" \
-H "Authorization: token <TOKEN>" \
https://api.github.com/repos/OWNER/REPO/issues \
-d '{"title":"Found a bug","body":"I'\''m having a problem with this.","assignees":["octocat"],"milestone":1,"labels":["bug"]}'
$ curl https://echo.apifox.com/post -X POST -H "a: 3" -H "b: 4"
{
"args": {},
"data": "",
"files": {},
"form": {},
"headers": {
"A": "3",
"Accept": "*/*",
"B": "4",
"Connection": "close",
"Host": "echo.apifox.com",
"User-Agent": "curl/7.79.1"
},
"json": null,
"origin": "118.113.0.137",
"url": "https://echo.apifox.com/post"
}
--head/-I 发送 HEAD 请求，只需要返回 Response Header。
$ curl --head https://shanyue.tech HTTP/2 200 server: Tengine content-type: text/html; charset=utf-8 content-length: 33229 vary: Accept-Encoding date: Tue, 21 Jun 2022 05:54:24 GMT vary: Accept-Encoding x-oss-request-id: 62B15D1050ED1C32320FE906 x-oss-cdn-auth: success accept-ranges: bytes etag: "F540C0D57CDB57215AF11970EF4AAEF6" last-modified: Wed, 23 Mar 2022 14:57:44 GMT x-oss-object-type: Normal x-oss-hash-crc64ecma: 8545542358272103335 x-oss-storage-class: Standard x-oss-meta-mtime: 1648047444.796073379 cache-control: no-cache content-md5: 9UDA1XzbVyFa8Rlw70qu9g== x-oss-server-time: 27 ali-swift-global-savetime: 1655790864 via: cache12.l2cn3051[290,290,200-0,M], cache4.l2cn3051[291,0], kunlun6.cn3145[383,382,200-0,M], kunlun3.cn3145[386,0] x-cache: MISS TCP_MISS dirn:-2:-2 x-swift-savetime: Tue, 21 Jun 2022 05:54:24 GMT x-swift-cachetime: 0 timing-allow-origin: * eagleid: 791d26a916557908641262834e
--include/-i，打印 Response Header 与 Response Body。
HTTP/1.1 200 OK access-control-allow-origin: * content-type: text/plain; charset=utf-8 content-length: 15 date: Wed, 17 Aug 2022 01:56:20 GMT x-envoy-upstream-service-time: 1 strict-transport-security: max-age=2592000; includeSubDomains server: istio-envoy Via: 1.1 google 222.222.222.113%
--verbose/-v，查看发送报文及 TLS handshake 的详细。
$ curl -vvv --head https://shanyue.tech * Rebuilt URL to: https://shanyue.tech/ * Trying 218.91.183.88... * TCP_NODELAY set * Connected to shanyue.tech (218.91.183.88) port 443 (#0) * ALPN, offering h3 * ALPN, offering http/1.1 * successfully set certificate verify locations: * CAfile: /etc/pki/tls/certs/ca-bundle.crt CApath: none * TLSv1.3 (OUT), TLS handshake, Client hello (1): * TLSv1.3 (IN), TLS handshake, Server hello (2): * TLSv1.3 (IN), TLS handshake, [no content] (0): * TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8): * TLSv1.3 (IN), TLS handshake, [no content] (0): * TLSv1.3 (IN), TLS handshake, Certificate (11): * TLSv1.3 (IN), TLS handshake, [no content] (0): * TLSv1.3 (IN), TLS handshake, CERT verify (15): * TLSv1.3 (IN), TLS handshake, [no content] (0): * TLSv1.3 (IN), TLS handshake, Finished (20): * TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1): * TLSv1.3 (OUT), TLS handshake, [no content] (0): * TLSv1.3 (OUT), TLS handshake, Finished (20): * SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384 * ALPN, server accepted to use h3 * Server certificate: * subject: CN=shanyue.tech * start date: Feb 5 00:00:00 2022 GMT * expire date: Feb 6 23:59:59 2023 GMT * subjectAltName: host "shanyue.tech" matched cert's "shanyue.tech" * issuer: C=US; O=DigiCert Inc; OU=www.digicert.com; CN=Encryption Everywhere DV TLS CA - G1 * SSL certificate verify ok. * Using HTTP2, server supports multi-use * Connection state changed (HTTP/2 confirmed) * Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0 * TLSv1.3 (OUT), TLS app data, [no content] (0): * TLSv1.3 (OUT), TLS app data, [no content] (0): * TLSv1.3 (OUT), TLS app data, [no content] (0): * Using Stream ID: 1 (easy handle 0x55c5a8e24690) * TLSv1.3 (OUT), TLS app data, [no content] (0): > HEAD / HTTP/2 > Host: shanyue.tech > User-Agent: curl/7.61.1 > Accept: */* > * TLSv1.3 (IN), TLS handshake, [no content] (0): * TLSv1.3 (IN), TLS handshake, Newsession Ticket (4): * TLSv1.3 (IN), TLS handshake, [no content] (0): * TLSv1.3 (IN), TLS handshake, Newsession Ticket (4): * TLSv1.3 (IN), TLS app data, [no content] (0): * Connection state changed (MAX_CONCURRENT_STREAMS == 128)! * TLSv1.3 (OUT), TLS app data, [no content] (0): * TLSv1.3 (IN), TLS app data, [no content] (0): < HTTP/2 200 HTTP/2 200 < server: Tengine server: Tengine < content-type: text/html; charset=utf-8 content-type: text/html; charset=utf-8 < content-length: 33229 content-length: 33229 < vary: Accept-Encoding vary: Accept-Encoding < date: Tue, 21 Jun 2022 06:02:59 GMT date: Tue, 21 Jun 2022 06:02:59 GMT < vary: Accept-Encoding vary: Accept-Encoding < x-oss-request-id: 62B15F13F15BB231391FB3A8 x-oss-request-id: 62B15F13F15BB231391FB3A8 < x-oss-cdn-auth: success x-oss-cdn-auth: success < accept-ranges: bytes accept-ranges: bytes < etag: "F540C0D57CDB57215AF11970EF4AAEF6" etag: "F540C0D57CDB57215AF11970EF4AAEF6" < last-modified: Wed, 23 Mar 2022 14:57:44 GMT last-modified: Wed, 23 Mar 2022 14:57:44 GMT < x-oss-object-type: Normal x-oss-object-type: Normal < x-oss-hash-crc64ecma: 8545542358272103335 x-oss-hash-crc64ecma: 8545542358272103335 < x-oss-storage-class: Standard x-oss-storage-class: Standard < x-oss-meta-mtime: 1648047444.796073379 x-oss-meta-mtime: 1648047444.796073379 < cache-control: no-cache cache-control: no-cache < content-md5: 9UDA1XzbVyFa8Rlw70qu9g== content-md5: 9UDA1XzbVyFa8Rlw70qu9g== < x-oss-server-time: 3 x-oss-server-time: 3 < ali-swift-global-savetime: 1655791379 ali-swift-global-savetime: 1655791379 < via: cache24.l2et15-1[66,66,200-0,M], cache44.l2et15-1[67,0], cache27.cn4056[128,128,200-0,M], cache64.cn4056[130,0] via: cache24.l2et15-1[66,66,200-0,M], cache44.l2et15-1[67,0], cache27.cn4056[128,128,200-0,M], cache64.cn4056[130,0] < x-cache: MISS TCP_MISS dirn:-2:-2 x-cache: MISS TCP_MISS dirn:-2:-2 < x-swift-savetime: Tue, 21 Jun 2022 06:02:59 GMT x-swift-savetime: Tue, 21 Jun 2022 06:02:59 GMT < x-swift-cachetime: 0 x-swift-cachetime: 0 < timing-allow-origin: * timing-allow-origin: * < eagleid: 088432cc16557913793393217e eagleid: 088432cc16557913793393217e < * Connection #0 to host shanyue.tech left intact
--location/-L，追踪重定向。
# 重定向两次后请求到数据 $ curl --location http://zhihu.com # 可使用 --head，查看到三次响应 $ curl --head --location http://zhihu.com
httpie 是现代化更为流行的一个 HTTP 客户端，支持色彩、JSON 等。
# 发送 JSON 数据给服务器端，httpie 比 curl 方便很多，不需要自己手写 header，curl 默认为 application/x-www-form-urlencoded
$ http POST https://echo.apifox.com/post "a: 3" name=shanyue
$ curl -X POST https://echo.apifox.com/post -H "a: 3" -H "content-type: application/json" -d '{"name": "shanyue"}'
# 发送 Form 数据给服务器端，curl/httpie 都比较方便
$ http POST https://echo.apifox.com/post "a: 3" name=shanyue
$ curl -X POST https://echo.apifox.com/post -H "a: 3" -d name=shanyue
# 上传文件
$ http POST https://echo.apifox.com/post < Readme.md
$ curl -X POST https://echo.apifox.com/post -H "content-type: application/json" -d @Readme.md
# multipart 上传文件
$ http --multipart https://echo.apifox.com/post a=3 b@'Readme.md'
在 Apifox Echo 中，还可以将请求直接转化为命令行。
