psql - PostgreSQL: Up and Running - page 45

CHAPTER 3
psql
psql is the de rigueur command-line utility packaged with PostgreSQL. Aside from its
most common use of running queries, you can use psql as an automated scripting tool;
as a tool for importing or exporting data, restoring tables, and database administration;
and even as a minimalistic reporting tool. As with other command-line tools, you have
to be familiar with a myriad of options. If you have access only to a server's command
line with no GUI, psql is pretty much your only choice for querying and managing
PostgreSQL. If you fall into this category, we suggest that you print out the dump of psql
help from the “psql Interactive Commands” on page 199 and frame it right above your
workstation.
Environment Variables
As in the other command-line tools packaged with PostgreSQL, you can forgo explicitly
specifying your host, port, and user by setting the PGHOST , PGPORT , and PGUSER envi‐
ronment variables as described in Environment Variables . You can also set your pass‐
word in PGPASSWORD or use a password file as described in The Password File . psql since
version 9.2 accepts two new environment variables:
PSQL_HISTORY
Sets the name of the psql history file that lists all commands executed in the recent
past. The default is ~/.psql_history .
PSQLRC
Sets the location and name of the configuration file.
If you omit the parameters without having set the environment variables, psql will use
the standard defaults. In the examples in this chapter, we'll assume you are using default
values or have these variables set. If you're using pgAdmin as well, you can jump right
to psql using the plug-in interface (see “Accessing psql from pgAdmin” on page 61 ). A