Encode username and password in Linux different from Postman

Hi all,

I have a problem when I use basic auth:

  • When I use basic auth in Postman, username and password will respond string 1 (this string is right and I can use this to work).
  • When I use encode with terminal Linux (CentOS7), it will respond string 2.
    String 2 is different from string 1. Same input but different output

Example you can try:
username:MT6NqGSTPKjsMjfvFg
password:Ub8LBR2YkNWP2Y4VwsMJVsp3SHGdNR28

Please help me or give me advice on how can I encode username and password in CentOS the same with Postman.
Warm Regards.
PhongTD