{ "version": "https://jsonfeed.org/version/1", "title": "Vault — Joie Llantero", "home_page_url": "https://sudojoie.com/vault", "description": "sudojoie Blog", "items": [ { "id": "https://sudojoie.com/vault/curl-cheat-sheet", "content_html": "

A quick reference for curl,a command-line tool for transferring data with URLs. Supports HTTP, HTTPS, FTP, SFTP, and more.

\n

Anatomy of a curl command​

\n
curl [options] [URL]
 │
 ├── -X METHOD       HTTP method (GET, POST, PUT, PATCH, DELETE)
 ├── -H \"K: V\"       Request header
 ├── -d \"data\"       Request body
 ├── -o file         Save output to file
 ├── -O              Save with remote filename
 ├── -u user:pass    Basic auth
 ├── -b \"k=v\"        Send cookie
 ├── -c file         Save cookies to file
 ├── -L              Follow redirects
 ├── -I              HEAD request (headers only)
 ├── -s              Silent (no progress bar)
 ├── -v              Verbose (show request + response headers)
 ├── -k              Skip TLS certificate verification
 └── --max-time N    Timeout after N seconds
\n
\n

HTTP Requests​

\n
# GET
curl https://example.com/api/users

# POST with JSON body
curl -X POST https://example.com/api/users \\
  -H \"Content-Type: application/json\" \\
  -d '{\"name\":\"joie\",\"role\":\"admin\"}'

# POST form data
curl -X POST https://example.com/login \\
  -d \"username=joie&password=secret\"

# PUT
curl -X PUT https://example.com/api/users/1 \\
  -H \"Content-Type: application/json\" \\
  -d '{\"name\":\"joie updated\"}'

# PATCH
curl -X PATCH https://example.com/api/users/1 \\
  -H \"Content-Type: application/json\" \\
  -d '{\"role\":\"user\"}'

# DELETE
curl -X DELETE https://example.com/api/users/1
\n
\n

Headers & Auth​

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# Custom header
curl -H \"Authorization: Bearer TOKEN\" https://example.com/api

# Multiple headers
curl -H \"Accept: application/json\" \\
     -H \"X-Request-ID: abc123\" \\
     https://example.com/api

# Basic auth
curl -u username:password https://example.com/protected

# API key in header
curl -H \"X-API-Key: mykey123\" https://example.com/api
\n
\n

File Upload / Download​

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# Download a file (save with remote name)
curl -O https://example.com/file.tar.gz

# Download and rename
curl -o myfile.tar.gz https://example.com/file.tar.gz

# Resume interrupted download
curl -C - -O https://example.com/largefile.tar.gz

# Upload a file (multipart form)
curl -X POST https://example.com/upload \\
  -F \"file=@/path/to/file.txt\"

# Upload raw binary
curl -X PUT https://example.com/upload \\
  --data-binary @/path/to/image.png
\n
\n

TLS / Certificates​

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# Skip certificate verification (insecure)
curl -k https://self-signed.example.com

# Specify CA cert
curl --cacert /path/to/ca.crt https://example.com

# Client certificate + key
curl --cert client.crt --key client.key https://example.com

# Show certificate info only
curl -v --head https://example.com 2>&1 | grep -A5 \"certificate\"
\n
\n

Cookies​

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# Send a cookie
curl -b \"session=abc123\" https://example.com

# Save cookies from response
curl -c cookies.txt https://example.com/login \\
  -d \"username=joie&password=secret\"

# Replay saved cookies
curl -b cookies.txt https://example.com/dashboard
\n
\n

Debugging & Inspection​

\n
# Show response headers only (HEAD)
curl -I https://example.com

# Show request + response headers
curl -v https://example.com

# Show only status code
curl -o /dev/null -s -w \"%{http_code}\" https://example.com

# Show timing breakdown
curl -o /dev/null -s -w \\
  \"dns:%{time_namelookup}s  connect:%{time_connect}s  ttfb:%{time_starttransfer}s  total:%{time_total}s\\n\" \\
  https://example.com

# Trace all data (very verbose)
curl --trace - https://example.com
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Proxy​

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# Route through HTTP proxy
curl -x http://proxy.example.com:8080 https://target.com

# Proxy with auth
curl -x http://proxy.example.com:8080 \\
  -U proxyuser:proxypass \\
  https://target.com

# SOCKS5 proxy (e.g. Tor)
curl --socks5 127.0.0.1:9050 https://check.torproject.org
\n
\n

Useful Combinations​

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# Pretty-print JSON response
curl -s https://api.example.com/data | python3 -m json.tool

# Follow redirects + show final URL
curl -Ls -o /dev/null -w \"%{url_effective}\" https://t.co/shortlink

# Rate-limit download speed
curl --limit-rate 500k -O https://example.com/bigfile.zip

# Retry on failure
curl --retry 3 --retry-delay 2 https://example.com/api

# Send request with timeout
curl --max-time 10 https://example.com/api
\n
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Quick Reference Card​

\n
FlagMeaning
-X METHODSet HTTP method
-H \"K: V\"Add request header
-d \"data\"Send request body
-F \"k=@file\"Multipart file upload
-o fileSave output to named file
-OSave with server filename
-C -Resume download
-LFollow redirects
-IHEAD (headers only)
-vVerbose output
-sSilent mode
-kIgnore TLS errors
-u user:passBasic authentication
-b \"k=v\"Send cookie
-c fileSave cookies
-x proxyUse proxy
--retry NRetry on failure
--max-time NGlobal timeout (seconds)
--limit-rate NCap transfer speed
", "url": "https://sudojoie.com/vault/curl-cheat-sheet", "title": "Curl Cheat Sheet", "summary": "A quick reference for using `curl`.", "date_modified": "2026-04-24T00:00:00.000Z", "author": { "name": "Joie Llantero", "url": "https://github.com/joiellantero" }, "tags": [ "Cmdline" ] }, { "id": "https://sudojoie.com/vault/welcome-to-the-vault", "content_html": "

The vault is a place for things that don't quite fit a blog post--quick notes, references, checklists, and writeups I want to keep somewhere findable.

\n

Not everything here will be polished. Some entries will be raw notes. Others will be more complete. Think of it as a personal wiki that's open to read.

", "url": "https://sudojoie.com/vault/welcome-to-the-vault", "title": "Welcome to the Vault", "summary": "What the vault is and how I plan to use it.", "date_modified": "2026-04-24T00:00:00.000Z", "author": { "name": "Joie Llantero", "url": "https://github.com/joiellantero" }, "tags": [ "Meta" ] } ] }