createlang [connection-option...] langname [dbname]
createlang [connection-option...] --list | -l dbname
createlang is a utility for adding a new programming language to a PostgreSQL database. createlang is just a wrapper around the CREATE LANGUAGE command.
createlang accepts the following command-line arguments:
Specifies the name of the procedural programming language to be defined.
Specifies to which database the language should be added. The default is to use the database with the same name as the current system user.
Display SQL commands as they are executed.
Show a list of already installed languages in the target database.
createlang also accepts the following command-line arguments for connection parameters:
Specifies the host name of the machine on which the server is running. If the value begins with a slash, it is used as the directory for the Unix domain socket.
Specifies the TCP port or local Unix domain socket file extension on which the server is listening for connections.
User name to connect as.
Force createlang to prompt for a password before connecting to a database.
This option is never essential, since createlang will automatically prompt for a password if the server demands password authentication. However, createlang will waste a connection attempt finding out that the server wants a password. In some cases it is worth typing -W to avoid the extra connection attempt.
Default connection parameters
This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Section 30.12).
Most error messages are self-explanatory. If not, run createlang with the --echo option and see under the respective SQL command for details. Also, any default connection settings and environment variables used by the libpq front-end library will apply.
Use droplang to remove a language.
To install the language pltcl into the database template1:
$ createlang pltcl template1
Note that installing the language into template1 will cause it to be automatically installed into subsequently-created databases as well.