list outputs a simple report to get a quick overview about credentials:
AccessKeyId         	Age 	Status  	LastUsed                      	Username
AKIAUGGSTKSE4EZDC3PO	1   	Inactive	never                         	IamRobot
AKIAUGGSTKSE7KBIR2D2	38  	Active  	2019-10-22 07:02:00 +0000 UTC 	IamRobot
all outputs the same report with all credentials for the current account.
new creates a new pair of credentials and (optionally) writes them to ~/.aws/credentials file.
All commands can be seen with credentials -h:
Description:
    AWS Credential manager
Sub-commands:
    credentials all       Displays a list of all keys for the current account
    credentials check     Check access key ages. Fail if any are older than set days
    credentials delete    Delete a key, shortcut: rm
    credentials disable   Disable (deactivate) a key
    credentials enable    Enable (activate) a key
    credentials list      List access keys, shortcut: ls
    credentials new       Create a new key
Run -h with subcommand to see usage:
$ credentials new -h
credentials new [--write] [--username=string]
Description:
    Create a new key
Options:
    -w, --write      Write new key to credentials file
    -u, --username   User to whom key will be created
go get -v github.com/kerma/aws-credentials/cmd/credentials