The ~/.psqlrc file determines the behavior of psql interactive command line client. Just like bashrc, psql client utility attempts to read and execute commands from the system-wide psqlrc file and the user’s ~/.psqlrc file before starting up. (On Windows, the user’s startup file is named %APPDATA%\postgresql\psqlrc.conf.)

The location of the user’s ~/.psqlrc file can also be set explicitly via the PSQLRC environment setting.

There can be multiple psqlrc files, the system-wide psqlrc file and the user’s ~/.psqlrc file can be made psql-version-specific by appending a dash and the PostgreSQL major or minor psql release number, for example ~/.psqlrc-9.2 or ~/.psqlrc-9.2.5. Version specific file always gets the preference when you have multiple psqlrc files.There are several options that you can add to customize psqlrc file and here is the description how to use them.

A good look at this file can lead to a better understanding of psqlrc : psql startup file for postgres

-----------------------------------------
-- psqlrc file to set psql preferences --
-- Author : Prashanth Goriparthi       --
-----------------------------------------

\set QUIET ON

\set PROMPT1 '%[%033[1;32;40m%]%M:%> %n@%/%[%033[0m%]% # '
\set PAGER OFF
\set HISTFILE ~/.psql_history- :HOST - : DBNAME -- Remove space between : and DBNAME
\set HISTSIZE 2000
\set ECHO_HIDDEN ON
\set COMP_KEYWORD_CASE upper

\timing
\encoding unicode

\pset null 'NULL'
\pset border 2

\set QUIET OFF

\echo '\nCurrent Host Server Date Time : '`date` '\n'

\echo 'Administrative queries:\n'
\echo '\t\t\t:settings\t-- Server Settings'
\echo '\t\t\t:conninfo\t-- Server connections'
\echo '\t\t\t:activity\t-- Server activity'
\echo '\t\t\t:locks\t\t-- Lock info'
\echo '\t\t\t:waits\t\t-- Waiting queires'
\echo '\t\t\t:dbsize\t\t-- Database Size'
\echo '\t\t\t:tablesize\t-- Tables Size'
\echo '\t\t\t:uselesscol\t-- Useless columns'
\echo '\t\t\t:uptime\t\t-- Server uptime'
\echo '\t\t\t:menu\t\t-- Help Menu'
\echo '\t\t\t\\h\t\t-- Help with SQL commands'
\echo '\t\t\t\\?\t\t-- Help with psql commands\n'

\echo 'Development queries:\n'
\echo '\t\t\t:sp\t\t-- Current Search Path'
\echo '\t\t\t:clear\t\t-- Clear screen'
\echo '\t\t\t:ll\t\t-- List\n'

-- Administration queries

\set menu '\\i ~/.psqlrc'

\set settings 'select name, setting,unit,context from pg_settings;'

\set locks  'SELECT bl.pid AS blocked_pid, a.usename AS blocked_user, kl.pid AS blocking_pid, ka.usename AS blocking_user, a.query AS blocked_statement FROM pg_catalog.pg_locks bl JOIN pg_catalog.pg_stat_activity a ON bl.pid = a.pid JOIN pg_catalog.pg_locks kl JOIN pg_catalog.pg_stat_activity ka ON kl.pid = ka.pid ON bl.transactionid = kl.transactionid AND bl.pid != kl.pid WHERE NOT bl.granted;'

\set conninfo 'select usename, count(*) from pg_stat_activity group by usename;'

\set activity 'select datname, pid, usename, application_name,client_addr, client_hostname, client_port, query, state from pg_stat_activity;'

\set waits 'SELECT pg_stat_activity.pid, pg_stat_activity.query, pg_stat_activity.waiting, now() - pg_stat_activity.query_start AS \"totaltime\", pg_stat_activity.backend_start FROM pg_stat_activity WHERE pg_stat_activity.query !~ \'%IDLE%\'::text AND pg_stat_activity.waiting = true;'

\set dbsize 'SELECT datname, pg_size_pretty(pg_database_size(datname)) db_size FROM pg_database ORDER BY db_size;'

\set tablesize 'SELECT nspname || \'.\' || relname AS \"relation\", pg_size_pretty(pg_relation_size(C.oid)) AS "size" FROM pg_class C LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace) WHERE nspname NOT IN (\'pg_catalog\', \'information_schema\') ORDER BY pg_relation_size(C.oid) DESC LIMIT 40;'

\set uselesscol 'SELECT nspname, relname, attname, typname, (stanullfrac*100)::int AS null_percent, case when stadistinct >= 0 then stadistinct else abs(stadistinct)*reltuples end AS \"distinct\", case 1 when stakind1 then stavalues1 when stakind2 then stavalues2 end AS \"values\" FROM pg_class c JOIN pg_namespace ns ON (ns.oid=relnamespace) JOIN pg_attribute ON (c.oid=attrelid) JOIN pg_type t ON (t.oid=atttypid) JOIN pg_statistic ON (c.oid=starelid AND staattnum=attnum) WHERE nspname NOT LIKE E\'pg\\\\_%\' AND nspname != \'information_schema\' AND relkind=\'r\' AND NOT attisdropped AND attstattarget != 0 AND reltuples >= 100 AND stadistinct BETWEEN 0 AND 1 ORDER BY nspname, relname, attname;'

\set uptime 'select now() - pg_postmaster_start_time() AS uptime;'

-- Development queries:

\set sp 'SHOW search_path;'
\set clear '\\! clear;'
\set ll '\\! ls -lrt;'

Once you login into database server using psql on command line your environment looks like the following: