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.

INSTALL

sudo apt install systemd

sudo dnf install systemd

sudo pacman -S systemd

sudo zypper install systemd

brew install systemd

nix profile install nixpkgs#systemd

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.