ZMQ\_IPC(7) 0MQ Manual ZMQ\_IPC(7)

# [NAME](#NAME)

zmq\_ipc - 0MQ local inter-process communication transport

# [SYNOPSIS](#SYNOPSIS)

The inter-process transport passes messages between local processes using a system-dependent IPC mechanism.

**Note**

The inter-process transport is currently only implemented on operating systems that provide UNIX domain sockets.

# [ADDRESSING](#ADDRESSING)

A 0MQ endpoint is a string consisting of a *transport*:// followed by an *address*. The *transport* specifies the underlying protocol to use. The *address* specifies the transport-specific address to connect to.

For the inter-process transport, the transport is ipc, and the meaning of the *address* part is defined below.

## [Binding a socket](#Binding_a_socket)

When binding a *socket* to a local address using *zmq\_bind()* with the *ipc* transport, the *endpoint* shall be interpreted as an arbitrary string identifying the *pathname* to create. The *pathname* must be unique within the operating system namespace used by the *ipc* implementation, and must fulfill any restrictions placed by the operating system on the format and length of a *pathname*.

When the address is wild-card \*, *zmq\_bind()* shall generate a unique temporary pathname. The caller should retrieve this pathname using the ZMQ\_LAST\_ENDPOINT socket option. See [**zmq\_getsockopt**(3)](/man/os/zeromq/zmq_getsockopt.3) for details.

**Note**

any existing binding to the same endpoint shall be overridden. That is, if a second process binds to an endpoint already bound by a process, this will succeed and the first process will lose its binding. In this behaviour, the *ipc* transport is not consistent with the *tcp* or *inproc* transports.

**Note**

the endpoint pathname must be writable by the process. When the endpoint starts with */*, e.g., ipc:///pathname, this will be an *absolute* pathname. If the endpoint specifies a directory that does not exist, the bind shall fail.

**Note**

on Linux only, when the endpoint pathname starts with @, the abstract namespace shall be used. The abstract namespace is independent of the filesystem and if a process attempts to bind an endpoint already bound by a process, it will fail. See [unix(7)](/man/os/zeromq/unix.7) for details.

**Note**

IPC pathnames have a maximum size that depends on the operating system. On Linux, the maximum is 113 characters including the "ipc://" prefix (107 characters for the real path name).

## [Unbinding wild-card address from a socket](#Unbinding_wild)

When wild-card * *endpoint* was used in *zmq\_bind()*, the caller should use real *endpoint* obtained from the ZMQ\_LAST\_ENDPOINT socket option to unbind this *endpoint* from a socket using *zmq\_unbind()*.

## [Connecting a socket](#Connecting_a_socket)

When connecting a *socket* to a peer address using *zmq\_connect()* with the *ipc* transport, the *endpoint* shall be interpreted as an arbitrary string identifying the *pathname* to connect to. The *pathname* must have been previously created within the operating system namespace by assigning it to a *socket* with *zmq\_bind()*.

# [EXAMPLES](#EXAMPLES)

**Assigning a local address to a socket**.

```
//  Assign the pathname "/tmp/feeds/0"
rc = zmq_bind(socket, "ipc:///tmp/feeds/0");
assert (rc == 0);
```

**Connecting a socket**.

```
//  Connect to the pathname "/tmp/feeds/0"
rc = zmq_connect(socket, "ipc:///tmp/feeds/0");
assert (rc == 0);
```

# [SEE ALSO](#SEE_ALSO)

[**zmq\_bind**(3)](/man/os/zeromq/zmq_bind.3) [**zmq\_connect**(3)](/man/os/zeromq/zmq_connect.3) [**zmq\_inproc**(7)](/man/os/zeromq/zmq_inproc.7) [**zmq\_tcp**(7)](/man/os/zeromq/zmq_tcp.7) [**zmq\_pgm**(7)](/man/os/zeromq/zmq_pgm.7) [**zmq\_vmci**(7)](/man/os/zeromq/zmq_vmci.7) [**zmq\_getsockopt**(3)](/man/os/zeromq/zmq_getsockopt.3) [**zmq**(7)](/man/os/zeromq/zmq.7)

# [AUTHORS](#AUTHORS)

This page was written by the 0MQ community. To make a change please read the 0MQ Contribution Policy at **http://www.zeromq.org/docs:contributing**.

10/24/2026 0MQ 4.3.5

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Document: zmq_ipc(7) from zeromq 4.3.5-r14 (Chainguard OS)
Source: https://github.com/zeromq/libzmq