本节简单介绍了PostgreSQL数据库启动时socket存储的目录的配置，其对应的参数为unix_socket_directories。 unix_socket_directories参数默认为/tmp，由于该目录是临时目录，以免误操作，一般设置在其他目录中。 下面把unix_socket_directories设置为/data/pg12，重新启动 ``` [pg12@localhost pg120db]$ grep 'unix' postgresql.conf unix_socket_directories = '/data/pg12' # comma-separated list of directories #unix_socket_directories = '/tmp' # comma-separated list of directories #unix_socket_group = '' # (change requires restart) #unix_socket_permissions = 0777 # begin with 0 to use octal notation [pg12@localhost pg120db]$ [pg12@localhost pg120db]$ pg_ctl restart pg_ctl: PID file "/data/pgsql/pg120db/postmaster.pid" does not exist Is server running? trying to start server anyway waiting for server to start....2019-11-18 18:17:35.123 CST [15542] LOG: starting PostgreSQL 12.0 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-16), 64-bit 2019-11-18 18:17:35.123 CST [15542] LOG: listening on IPv4 address "0.0.0.0", port 5432 2019-11-18 18:17:35.123 CST [15542] LOG: listening on IPv6 address "::", port 5432 2019-11-18 18:17:35.155 CST [15542] LOG: listening on Unix socket "/data/pg12/.s.PGSQL.5432" 2019-11-18 18:17:35.237 CST [15542] LOG: redirecting log output to logging collector process 2019-11-18 18:17:35.237 CST [15542] HINT: Future log output will appear in directory "pg_log". done server started ``` 尝试连接数据库 ``` [pg12@localhost pg120db]$ psql -d testdb psql: error: could not connect to server: could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket "/tmp/.s.PGSQL.5432"? ``` 提示找不到socket（默认在/tmp下），可使用指定主机&端口连接 ``` ``` 但这样的连接方式不是本地连接 ``` [pg12@localhost ~]$ netstat -anpo|grep psql (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) tcp6 0 0 ::1:52206 ::1:5432 ESTABLISHED 16200/psql keepalive (7207.79/0/0) ``` 设置参数PGHOST，使用本地连接(PGHOST behaves the same as the host connection parameter.) ``` [pg12@localhost pg120db]$ export PGHOST=/data/pg12 [pg12@localhost pg120db]$ psql -d testdb Expanded display is used automatically. psql (12.0) Type "help" for help. ... [pg12@localhost ~]$ netstat -anpo|grep psql (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) unix 3 [ ] STREAM CONNECTED 876042 15681/psql [pg12@localhost ~]$ ``` 或者使用-h指定为socket所在目录 ``` [pg12@localhost ~]$ psql -h /data/pg12 Expanded display is used automatically. psql (12.0) Type "help" for help. [local:/data/pg12]:5432 pg12@testdb=# ... [pg12@localhost ~]$ netstat -anpo|grep psql (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) unix 3 [ ] STREAM CONNECTED 880596 16309/psql [pg12@localhost ~]$ ``` **参考资料** [Environment Variables](https://www.postgresql.org/docs/12/libpq-envars.html)