# passwd -u dummyo
Updating password for user: dummyo
Enter current password:
Enter new password:
Enter new password again:
Password was not changed: EDC5143I No such process. (errno2=0x090C05DC)
Release : 16.0
Component : CA ACF2 for z/OS
Based on our findings it is a function/requirement of the passwd command that if
using the passwd AIX command to change a password the logonid must be defined to OMVS.
The IBM documentation related to the passwd command also mentions:
To change another user's password, enter the passwd command and the user's login
name (the User parameter). The passwd command prompts you for the old password
of the user as well as the new password.