Supplies the current Perforce user’s password for any Perforce command.

Perforce passwords are set via p4 passwd, or in the form invoked by p4 user. The setting of P4PASSWD is used to verify the user’s identity. If a password has not been set, the value P4PASSWD is not used, even if set.

While it is possible to manually set the P4PASSWD environment variable to your plaintext password, the more secure way is to use the p4 passwd command. On UNIX, this will invoke a challenge/response mechanism which securely verifies your password. On Windows, this sets P4PASSWD to the encrypted MD5 hash of your password.

On Windows platforms, if you set a password in P4V, the value of the registry variable P4PASSWD is set for you. Setting the password in P4V is like using p4 passwd (or p4 set P4PASSWD) from the MS-DOS command line, setting the registry variable to the encrypted MD5 hash of the password. The unencrypted password itself is never stored in the registry.

If you are using ticket-based authentication, but have a script that relies on a P4PASSWD setting, use p4 login -p to display the value of a ticket that can be passed to Perforce commands as though it were a password (that is, either from the command line, or by setting P4PASSWD to the value of the valid ticket).