To demonstrate switchover, we will assume a replication cluster with a primary (node1) and one standby (node2); after the switchover node2 should become the primary with node1 following it.

The switchover command must be run from the standby which is to be promoted, and in its simplest form looks like this:

    $ repmgr -f /etc/repmgr.conf standby switchover
    NOTICE: executing switchover on node "node2" (ID: 2)
    INFO: searching for primary node
    INFO: checking if node 1 is primary
    INFO: current primary node is 1
    INFO: SSH connection to host "node1" succeeded
    INFO: archive mode is "off"
    INFO: replication lag on this standby is 0 seconds
    NOTICE: local node "node2" (ID: 2) will be promoted to primary; current primary "node1" (ID: 1) will be demoted to standby
    NOTICE: stopping current primary node "node1" (ID: 1)
    NOTICE: issuing CHECKPOINT
    DETAIL: executing server command "pg_ctl -l /var/log/postgres/startup.log -D '/var/lib/pgsql/data' -m fast -W stop"
    INFO: checking primary status; 1 of 6 attempts
    NOTICE: current primary has been cleanly shut down at location 0/3001460
    NOTICE: promoting standby to primary
    DETAIL: promoting server "node2" (ID: 2) using "pg_ctl -l /var/log/postgres/startup.log -w -D '/var/lib/pgsql/data' promote"
    server promoting
    NOTICE: STANDBY PROMOTE successful
    DETAIL: server "node2" (ID: 2) was successfully promoted to primary
    INFO: setting node 1's primary to node 2
    NOTICE: starting server using  "pg_ctl -l /var/log/postgres/startup.log -w -D '/var/lib/pgsql/data' restart"
    NOTICE: NODE REJOIN successful
    DETAIL: node 1 is now attached to node 2
    NOTICE: switchover was successful
    DETAIL: node "node2" is now primary
    NOTICE: STANDBY SWITCHOVER is complete
   

The old primary is now replicating as a standby from the new primary, and the cluster status will now look like this:

    $ repmgr -f /etc/repmgr.conf cluster show
     ID | Name  | Role    | Status    | Upstream | Location | Connection string
    ----+-------+---------+-----------+----------+----------+--------------------------------------
     1  | node1 | standby |   running | node2    | default  | host=node1 dbname=repmgr user=repmgr
     2  | node2 | primary | * running |          | default  | host=node2 dbname=repmgr user=repmgr
   

If repmgrd is in use, it's worth double-checking that all nodes are unpaused by executing repmgr service status (repmgr 4.2 - 4.4: repmgr daemon status).