The init or initdb mode creates a new PostgreSQL database cluster, that is, a collection of databases that will be managed by a single server instance. This mode invokes the initdb command. See initdb(1) for details.
start mode launches a new server. The server is started in the background, and its standard input is attached to /dev/null (or nul on Windows). On Unix-like systems, by default, the server's standard output and standard error are sent to pg_ctl's standard output (not standard error). The standard output of pg_ctl should then be redirected to a file or piped to another process such as a log rotating program like rotatelogs; otherwise postgres will write its output to the controlling terminal (from the background) and will not leave the shell's process group. On Windows, by default the server's standard output and standard error are sent to the terminal. These default behaviors can be changed by using -l to append the server's output to a log file. Use of either -l or output redirection is recommended.
stop mode shuts down the server that is running in the specified data directory. Three different shutdown methods can be selected with the -m option. "Smart" mode waits for all active clients to disconnect and any online backup to finish. If the server is in hot standby, recovery and streaming replication will be terminated once all clients have disconnected. "Fast" mode (the default) does not wait for clients to disconnect and will terminate an online backup in progress. All active transactions are rolled back and clients are forcibly disconnected, then the server is shut down. "Immediate" mode will abort all server processes immediately, without a clean shutdown. This choice will lead to a crash-recovery cycle during the next server start.
restart mode effectively executes a stop followed by a start. This allows changing the postgres command-line options, or changing configuration-file options that cannot be changed without restarting the server. If relative paths were used on the command line during server start, restart might fail unless pg_ctl is executed in the same current directory as it was during server start.
reload mode simply sends the postgres server process a SIGHUP signal, causing it to reread its configuration files (postgresql.conf, pg_hba.conf, etc.). This allows changing configuration-file options that do not require a full server restart to take effect.
status mode checks whether a server is running in the specified data directory. If it is, the server's PID and the command line options that were used to invoke it are displayed. If the server is not running, pg_ctl returns an exit status of 3. If an accessible data directory is not specified, pg_ctl returns an exit status of 4.
promote mode commands the standby server that is running in the specified data directory to end standby mode and begin read-write operations.
kill mode sends a signal to a specified process. This is primarily valuable on Microsoft Windows which does not have a built-in kill command. Use --help to see a list of supported signal names.
register mode registers the PostgreSQL server as a system service on Microsoft Windows. The -S option allows selection of service start type, either "auto" (start service automatically on system startup) or "demand" (start service on demand).
unregister mode unregisters a system service on Microsoft Windows. This undoes the effects of the register command.
The options should usually be surrounded by single or double quotes to ensure that they are passed through as a group.
The initdb-options should usually be surrounded by single or double quotes to ensure that they are passed through as a group.
In init mode, this option analogously specifies the location of the initdb executable.
When waiting, pg_ctl repeatedly checks the server's PID file, sleeping for a short amount of time between checks. Startup is considered complete when the PID file indicates that the server is ready to accept connections. Shutdown is considered complete when the server removes the PID file. pg_ctl returns an exit code based on the success of the startup or shutdown.
If the operation does not complete within the timeout (see option -t), then pg_ctl exits with a nonzero exit status. But note that the operation might continue in the background and eventually succeed.
If waiting is disabled, the requested action is triggered, but there is no feedback about its success. In that case, the server log file or an external monitoring system would have to be used to check the progress and success of the operation.
In prior releases of PostgreSQL, this was the default except for the stop mode.
If an option is specified that is valid, but not relevant to the selected operating mode, pg_ctl ignores it.
Most pg_ctl modes require knowing the data directory location; therefore, the -D option is required unless PGDATA is set.
pg_ctl, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Section 34.14).
For additional variables that affect the server, see postgres(1).
To start the server, waiting until the server is accepting connections:
$ pg_ctl start
To start the server using port 5433, and running without fsync, use:
$ pg_ctl -o "-F -p 5433" start
To stop the server, use:
$ pg_ctl stop
The -m option allows control over how the server shuts down:
$ pg_ctl stop -m smart
Restarting the server is almost equivalent to stopping the server and starting it again, except that by default, pg_ctl saves and reuses the command line options that were passed to the previously-running instance. To restart the server using the same options as before, use:
$ pg_ctl restart
But if -o is specified, that replaces any previous options. To restart using port 5433, disabling fsync upon restart:
$ pg_ctl -o "-F -p 5433" restart
Here is sample status output from pg_ctl:
$ pg_ctl status pg_ctl: server is running (PID: 13718) /usr/local/pgsql/bin/postgres "-D" "/usr/local/pgsql/data" "-p" "5433" "-B" "128"
The second line is the command that would be invoked in restart mode.