systemd-socket-activate

Test socket activation of daemons

TLDR

Listen on a port and launch a command on connection

$ systemd-socket-activate -l [8080] [command]

Listen on multiple ports for a command

$ systemd-socket-activate -l [8080] -l [8081] [command]

Accept connections and spawn a new instance for each

$ systemd-socket-activate -l [8080] -a [command]

Use datagram (UDP) sockets instead of stream (TCP)

$ systemd-socket-activate -l [8080] -d [command]

Set environment variables for the launched process

$ systemd-socket-activate -l [8080] -E [VAR=value] [command]

Run in inetd compatibility mode

$ systemd-socket-activate -l [8080] --inetd [command]

SYNOPSIS

systemd-socket-activate [options] command [arguments]

systemd-socket-activate is a test and development tool for socket activation. It listens on sockets and launches a specified command when connections arrive, simulating systemd's socket activation feature without needing to configure full socket and service unit files.By default it listens on a stream (TCP) socket. Use --datagram for UDP or --seqpacket for sequential packet sockets. The activated program receives the socket file descriptors via the $LISTEN_FDS protocol (or via stdin/stdout in --inetd mode).

PARAMETERS

-l ADDRESS, --listen=ADDRESS

Listen on the specified address (port number or host:port).

-a, --accept

Launch a new instance of the command for each connection. Cannot be combined with --now.

-d, --datagram

Listen on a datagram socket (SOCK_DGRAM) instead of a stream socket. Cannot be combined with --seqpacket.

--seqpacket

Listen on a sequential packet socket (SOCK_SEQPACKET) instead of a stream socket. Cannot be combined with --datagram.

-E VAR[=VALUE], --setenv=VAR[=VALUE]

Set an environment variable for the launched process. If no value given, inherits from the current environment.

--fdname=NAME[:NAME...]

Specify names for the file descriptors passed. Enables use of sdlistenfdswithnames(3).

--inetd

Use the inetd protocol for passing file descriptors (as stdin/stdout) instead of the $LISTEN_FDS protocol.

--now

Start the command immediately instead of waiting for a connection. Cannot be combined with --accept.

-h, --help

Display help information.

--version

Display version information.

CAVEATS

Primarily intended for testing, not production use. For production, configure proper systemd socket and service units. The service must support socket activation protocol. Part of the systemd suite.