psql --version

select version();

show server_version;

SHOW server_version_num;

SELECT current_setting('server_version_num');

SELECT current_setting(‘server_version_num');返回类型为text，如果需要可以转换为interger
SELECT current_setting('server_version_num')::integer;

$ psql -U peimsmdata -h 127.0.0.1 peimsm
could not change directory to "/root"
Password for user peimsmdata:
psql (9.2.23, server 9.6.3)
WARNING: psql version 9.2, server version 9.6.
   Some psql features might not work.
Type "help" for help.

$ psql --version
could not change directory to "/root"
psql (PostgreSQL) 9.2.23
# which -a psql
/usr/bin/psql
/usr/local/postgresql/bin/psql
/bin/psql
# mv /usr/bin/psql /usr/bin/psql.bak
# ln -s /usr/local/postgresql/bin/psql /usr/bin/psql
$ psql -U peimsmdata -h 127.0.0.1 peimsm
could not change directory to "/root": Permission denied
Password for user peimsmdata:
psql (9.6.3)
Type "help" for help.