Postgresql : syntax error at or near "-"

I have reproduced the issue in my system,

postgres=# alter user my-sys with password 'pass11';
ERROR:  syntax error at or near "-"
LINE 1: alter user my-sys with password 'pass11';
                       ^

Here is the issue,

psql is asking for input and you have given again the alter query see postgres-#That's why it's giving error at alter

postgres-# alter user "my-sys" with password 'pass11';
ERROR:  syntax error at or near "alter"
LINE 2: alter user "my-sys" with password 'pass11';
        ^

Solution is as simple as the error,

postgres=# alter user "my-sys" with password 'pass11';
ALTER ROLE

Wrap it in double quotes

alter user "dell-sys" with password 'Pass@133';

Notice that you will have to use the same case you used when you created the user using double quotes. Say you created "Dell-Sys" then you will have to issue exact the same whenever you refer to that user.

I think the best you do is to drop that user and recreate without illegal identifier characters and without double quotes so you can later refer to it in any case you want.