How to list the postgres processes running on your server and what their jobs are

A neet little trick I learned from the series "Mirage of memory, part 2: PSS"

ps -fu postgres | grep $(pgrep -f postmaster)
postgres    1913       1  0 Jul17 ?        00:02:51 /usr/pgsql-15/bin/postmaster -D /var/lib/pgsql/15/data/
postgres    1982    1913  0 Jul17 ?        00:00:24 postgres: logger
postgres    2063    1913  0 Jul17 ?        00:00:18 postgres: checkpointer
postgres    2064    1913  0 Jul17 ?        00:00:03 postgres: background writer
postgres    2119    1913  0 Jul17 ?        00:00:07 postgres: walwriter
postgres    2120    1913  0 Jul17 ?        00:00:14 postgres: autovacuum launcher
postgres    2121    1913  0 Jul17 ?        00:00:01 postgres: archiver
postgres    2122    1913  0 Jul17 ?        00:00:00 postgres: logical replication launcher
postgres    2657    1913  0 Jul17 ?        00:02:05 postgres: postgres_exporter postgres localhost(48674) idle

The command lists all processes by user "postgres" and and greps for the output of the command "pgrep -f postmaster", which returns a list of process IDs

You could also count the number of processes by user "postgres" by simply typing

pgrep -c postmaster
9