PostgreSQL数据库psql连接报错connections on Unix domain socket “/opt/postgresgl/pgdata/.s.PGSQL.5432“?
[postgres@localhost ~]$ psql
psql: error: connection to server on socket "/opt/postgresql/pgdata/.s.PGSQL.5432" failed: 没有那个文件或目录
Is the server running locally and accepting connections on that socket?

今天安装了PostgreSQL数据库，在执行psql的时候 报错，报错内容如下：

[postgres@localhost ~]$ psql
psql: error: connection to server on socket "/opt/postgresql/pgdata/.s.PGSQL.5432" failed: 没有那个文件或目录
Is the server running locally and accepting connections on that socket?

问题分析：

1.查看查看参数unix_socket_directories

[postgres@localhost ~]$ cat /opt/postgresql/pgdata/postgresql.conf | grep unix_socket_directories
#unix_socket_directories = '/tmp'       # comma-separated list of directories

解决办法：

修改/opt/postgresql/pgdata/postgresql.conf文件中的unix_socket_directories参数，修改如下：

unix_socket_directories='/opt/postgresql/pgdata'

或者在psql中修改也可以

psql -h 127.0.0.1
alter system set unix_socket_directories to '/opt/postgresql/pgdata';

重新postgreSQL服务，问题解决。