only TCP/IP sockets can be used to connect to the server.

The default value is normally

<filename>/tmp</filename>, but that can be changed at build time.

On Windows, the default is empty, which means no Unix-domain socket is

created by default.

This parameter can only be set at server start.

</para>

created in each of the <varname>unix_socket_directories</varname> directories.

Neither file should ever be removed manually.

</para>

<para>

This parameter is irrelevant on Windows, which does not have

Unix-domain sockets.

</para>

</listitem>

</varlistentry>

</para>

<para>

This parameter isirrelevanton Windows, which does not have

Unix-domain sockets.

This parameter isnot supportedon Windows. Any setting will be

ignored.

</para>

</listitem>

</varlistentry>

10, that ignore socket permissions entirely. There, one can achieve a

similar effect by pointing <varname>unix_socket_directories</varname> to a

directory having search permission limited to the desired audience.

This parameter is also irrelevant on Windows, which does not have

Unix-domain sockets.

</para>

</listitem>

</varlistentry>

<para>

The host component is interpreted as described for the parameter <xref

linkend="libpq-connect-host"/>. In particular, a Unix-domain socket

connection is chosen if the host part is either empty or starts with a

slash, otherwise a TCP/IP connection is initiated. Note, however, that the

connection is chosen if the host part is either empty or looks like an

absolute path name,

otherwise a TCP/IP connection is initiated. Note, however, that the

slash is a reserved character in the hierarchical part of the URI. So, to

specify a non-standard Unix-domain socket directory, either omit the host

specification in the URI and specify the host as a parameter, or

<term><literal>host</literal></term>

<listitem>

<para>

Name of host to connect to.<indexterm><primary>host name</primary></indexterm>

If a host name begins with a slash, it specifies Unix-domain

communication rather than TCP/IP communication; the value is the

name of the directory in which the socket file is stored.

The default behavior when <literal>host</literal> is

not specified, or is empty, is to connect to a Unix-domain

Name of host to connect to.<indexterm><primary>host

name</primary></indexterm> If a host name looks like an absolute path

name, it specifies Unix-domain communication rather than TCP/IP

communication; the value is the name of the directory in which the

socket file is stored. (On Unix, an absolute path name begins with a

slash. On Windows, paths starting with drive letters are also

recognized.) The default behavior when <literal>host</literal> is not

specified, or is empty, is to connect to a Unix-domain

socket<indexterm><primary>Unix domain socket</primary></indexterm> in

<filename>/tmp</filename> (or whatever socket directory was specified

when <productname>PostgreSQL</productname> was built). On machines without

Unix-domain sockets, the default is to connect to <literal>localhost</literal>.

when <productname>PostgreSQL</productname> was built). On Windows and

on machines without Unix-domain sockets, the default is to connect to

<literal>localhost</literal>.

</para>

<para>

A comma-separated list of host names is also accepted, in which case

</para>

<para>

Without either a host name or host address,

<application>libpq</application> will connect using a

localUnix-domain socket; or on machines without Unix-domain

<application>libpq</application> will connect using a local

Unix-domain socket; or on Windows and on machines without Unix-domain

sockets, it will attempt to connect to <literal>localhost</literal>.

</para>

</listitem>

can use the <option>-s</option> option to put the socket files in some

directory with a shorter path name. For security, be sure that that

directory is not readable or writable by any other users.

(This is notrelevant on Windows.)

(This is notsupported on Windows.)

</para>

<para>

cluster data directory path,

postmaster start timestamp,

port number,

Unix-domain socket directory path (empty on Windows),

Unix-domain socket directory path (could be empty),

first valid listen_address (IP address or <literal>*</literal>, or empty if

not listening on TCP),

and shared memory segment ID