curl

transfer data with URLs

TLDR

Download file

$ curl -O [https://example.com/file.zip]

Save to specific file

$ curl -o [filename] [https://example.com/file]

POST data

$ curl -X POST -d ["key=value"] [https://api.example.com]

Follow redirects

$ curl -L [https://example.com]

Send JSON

$ curl -H ["Content-Type: application/json"] -d ['{"key":"value"}'] [https://api.example.com]

Show headers

$ curl -I [https://example.com]

curl is a command-line tool for transferring data with URLs. It supports HTTP, HTTPS, FTP, and many other protocols, making it essential for web development, API testing, and file transfers.The tool is ubiquitous in scripts, CI/CD pipelines, and system administration.

PARAMETERS

-O, --remote-name

Save with remote filename

-o, --output file

Save to specified file

-L, --location

Follow redirects

-X, --request method

HTTP method (GET, POST, PUT, DELETE)

-d, --data data

Send POST data

-H, --header header

Add custom header

-u, --user user:pass

Authentication

-I, --head

Fetch headers only

-v, --verbose

Verbose output

-s, --silent

Silent mode

-f, --fail

Fail silently on HTTP errors

-k, --insecure

Allow insecure SSL connections

-C, --continue-at offset

Resume a previous download (use `-` for auto)

--cookie data|file

Send cookies (inline string or file path)

--cookie-jar file

Write received cookies to file

--max-time seconds

Maximum time allowed for the transfer

--retry N

Retry failed transfers up to N times

-A, --user-agent string

Send User-Agent header

-e, --referer url

Send Referer header

CONFIGURATION

~/.curlrc

Default options loaded on every curl invocation (one option per line).

~/.netrc

Stores authentication credentials for remote hosts (used with --netrc).

INSTALL

sudo apt install curl

sudo dnf install curl

sudo pacman -S curl

sudo apk add curl

sudo zypper install curl

brew install curl

nix profile install nixpkgs#curl

CAVEATS

Silent failures by default (use -f to change). Large downloads show progress by default (use -s for scripts). Cookie files need management. SSL certificate issues require -k (insecure). Complex syntax for advanced features.

HISTORY

curl originated in 1996 as httpget (by Rafael Sagula, with Daniel Stenberg contributing), was renamed to urlget in 1997 when FTP support was added, and became curl with version 4.0 in March 1998. It is one of the most widely used command-line tools for data transfer.