If somebody removed postmaster.pid file In postgreSql what will happened in postgres server ?

If somebody removed postmaster.pid file Server will be going to down becouse postgres server running based on postmaster.pid file so you need to start the server manually  after started the postgres server posmaster.pid file will be created automatically

[root@p1 data]# pwd
/opt/PostgreSQL/9.3/data[
root@p1 data]# mv postmaster.pid  /home/
mv: overwrite `/home/postmaster.pid'? y



bash-3.2$ pg_ctl -D /opt/PostgreSQL/9.3/data/ status
pg_ctl: no server running

after started the postgres server postmaster process id will be varried see below example first one is old postmaster.pid file next is new postmaster.pid file
Old Postmaster.pid file:

[root@p1 home]# cat postmaster.pid 
13750
/opt/PostgreSQL/9.3/data
1494571616
5432
/tmp
*
  5432001   3932161

New Postmaster.pid file After started postgres server:

[root@p1 data]# cat postmaster.pid
13957
/opt/PostgreSQL/9.3/data
1494572359
5432
/tmp
*
  5432001   3964929