Added curl notes to the knowledge base

knowledge base/curl.md

@@ -0,0 +1,106 @@
+# cURL
+
+## TL;DR
+
+```shell
+# Send a single GET request and show its output on stdout.
+curl http://url.of/file
+
+# Be quiet.
+curl --silent https://www.example.com
+curl -s --show-error https://www.example.com
+
+# Download files.
+curl http://url.of/file -o path/to/file
+curl -O http://url.of/file1 -O http://url.of/file2
+curl http://url.of/file[1-24]
+
+# Resume downloads.
+curl -C - -o partial_file http://url.of/file
+
+# Limit downloads bandwidth.
+curl --limit-rate 1000B -O http://url.of/file
+
+# Follow redirects.
+curl -L http://url.of/file
+
+# Only fetch HTTP headers from a response.
+curl -I http://example.com
+
+# Only return the HTTP status code.
+curl -o /dev/null -w '%{http_code}\n' -s -I http://example.com
+
+# Send different request types.
+curl --request PUT http://example.com
+
+# Specify headers.
+curl http://example.com -H "Content-Type:application/json" http://example.com
+
+# Skip certificate validation.
+curl --insecure https://example.com
+
+# Pass certificates for a resource.
+curl --cert client.pem --key key.pem -k https://example.com
+curl --cacert ca.pem https://example.com
+
+# Authenticate.
+curl -u username:password http://url.of/file
+curl -u username:password -O ftp://url.of/file
+curl ftp://username:password@example.com
+
+# POST to a form.
+curl -F "name=user" -F "password=test" http://example.com
+curl --data 'name=bob' http://example.com/form
+
+# Send data.
+curl http://example.com -H "Content-Type:application/json" -d '{"name":"bob"}' -X POST
+curl http://example.com -H "Content-Type:application/json" -d @file.json -X POST
+
+# Use a proxy.
+curl http://example.com --proxy socks5://localhost:19999
+
+# Forcefully resolve a host to a given address.
+curl https://example.com --resolve example.com:443:google.com
+```
+
+## Apply settings to all connections
+
+Unless the `-q` option is used, `curl` always checks for a default config file on invocation and uses it if found.
+
+The default configuration file is looked for in the following places, in this order:
+
+1. `$CURL_HOME/.curlrc`
+1. `$XDG_CONFIG_HOME/.curlrc`, added in 7.73.0
+1. `$HOME/.curlrc`
+1. on Windows only: `%USERPROFILE%\.curlrc`
+1. on Windows only: `%APPDATA%\.curlrc`
+1. on Windows only: `%USERPROFILE%\Application Data\.curlrc`
+
+On Non-Windows hosts, `curl` uses `getpwuid` to find the user's home directory.
+
+On Windows, if curl finds no `.curlrc` file in the sequence described above, it will check for one in the same dir the curl executable is placed.
+
+```text
+# ~/.curlrc
+# Accepts both short and long options.
+# Options in long format are accepted without the leading two dashes to make it
+# easier to read.
+# Arguments must be provided on the same line of the option.
+# Arguments can be separated by space, '=' and ':'
+
+location
+--insecure
+--user-agent "my-agent"
+request = "PUT"
+config: "~/.config/curl"
+```
+
+## Sources
+
+- [cheat.sh]
+- [How to ignore invalid and self signed ssl connection errors with curl]
+- [Config file]
+
+[cheat.sh]: https://cheat.sh/curl
+[config file]: https://everything.curl.dev/cmdline/configfile
+[how to ignore invalid and self signed ssl connection errors with curl]: https://www.cyberciti.biz/faq/how-to-curl-ignore-ssl-certificate-warnings-command-option/