curl/docs/cmdline-opts/user.md

c	SPDX-License-Identifier	Long	Short	Arg	Help	Category	Added	Multi	See-also	Example
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.	curl	user	u	<user:password>	Server user and password	important auth	4.0	single	netrc config	-u user:secret $URL

--user

Specify the username and password to use for server authentication. Overrides --netrc and --netrc-optional.

If you simply specify the username, curl prompts for a password.

The username and passwords are split up on the first colon, which makes it impossible to use a colon in the username with this option. The password can, still.

On systems where it works, curl hides the given option argument from process listings. This is not enough to protect credentials from possibly getting seen by other users on the same system as they still are visible for a moment before cleared. Such sensitive data should be retrieved from a file instead or similar and never used in clear text in a command line.

When using Kerberos V5 with a Windows based server you should include the Windows domain name in the username, in order for the server to successfully obtain a Kerberos Ticket. If you do not, then the initial authentication handshake may fail.

When using NTLM, the username can be specified simply as the username, without the domain, if there is a single domain and forest in your setup for example.

To specify the domain name use either Down-Level Logon Name or UPN (User Principal Name) formats. For example, EXAMPLE\user and user@example.com respectively.

If you use a Windows SSPI-enabled curl binary and perform Kerberos V5, Negotiate, NTLM or Digest authentication then you can tell curl to select the username and password from your environment by specifying a single colon with this option: "-u :".