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public-inbox-daemon - Man Page

common usage for public-inbox network daemons




This manual describes common options and behavior for public-inbox network daemons.  Network daemons for public-inbox provide read-only IMAP, HTTP, NNTP and POP3 access to public-inboxes. Write access to a public-inbox will never be required to run these.

These daemons are implemented with a common core using non-blocking sockets and optimized for fairness; even with thousands of connected clients over slow links.

They also provide graceful shutdown/upgrade support to avoid breaking existing connections during software upgrades.

These daemons may also utilize multiple pre-forked worker processes to take advantage of multiple CPUs.


-l [PROTOCOL://]ADDRESS[?opt1=val1,opt2=val2]
--listen [PROTOCOL://]ADDRESS[?opt1=val1,opt2=val2]

This takes an absolute path to a Unix socket or HOST:PORT to listen on.  For example, to listen to TCP connections on port 119, use: -l  This may also point to a Unix socket (-l /path/to/http.sock) for a reverse proxy like nginx(8) to use.

May be specified multiple times to allow listening on multiple sockets.

Unless per-listener options are used (required for public-inbox-netd(1)), this does not need to be specified at all if relying on systemd.socket(5) or similar,

Per-listener options may be specified after ? as KEY=VALUE pairs delimited by ,.  See public-inbox-netd(1) for documentation on the cert=, key=, env.NAME=VALUE, out=, err=, and psgi= options available.

Default: server-dependent unless socket activation is used with systemd(1) or similar (see systemd.socket(5)).

--stdout PATH

Specify an appendable path to redirect stdout descriptor (1) to. Using this is preferable to setting up the redirect externally (e.g. >>/path/to/log in shell) since it allows SIGUSR1 to be handled (see "Signals" in Signals below).

out= may also be specified on a per-listener basis.

Default: /dev/null with --daemonize, inherited otherwise

--stderr PATH

Like --stdout, but for the stderr descriptor (2).

err= may also be specified on a per-listener basis.

Default: /dev/null with --daemonize, inherited otherwise


Set the number of worker processes.

Normally, this should match the number of CPUs on the system to take full advantage of the hardware.  However, users of memory-constrained systems may want to lower this.

Setting this to zero (-W0) disables the master/worker split; saving some memory but removing the ability to use SIGTTIN to increase worker processes or have the worker restarted by the master on crashes.

Default: 1

--cert /path/to/cert

The default TLS certificate for HTTPS, IMAPS, NNTPS, POP3S and/or STARTTLS support if the cert option is not given with --listen.

Well-known TCP ports automatically get TLS or STARTTLS support If using systemd-compatible socket activation and a TCP listener on port well-known ports (563 is inherited, it is automatically NNTPS when this option is given.  When a listener on port 119 is inherited and this option is given, it automatically gets STARTTLS support.

--key /path/to/key

The default TLS certificate key for the default --cert or per-listener cert= option.  The private key may be concatenated into the path used by the cert, in which case this option is not needed.

--multi-accept INTEGER

By default, each worker accepts one connection at-a-time to maximize fairness and minimize contention across multiple processes on a shared listen socket.  Accepting multiple connections at once may be useful in constrained deployments with few, heavily-loaded workers. Negative values enables a worker to accept all available clients at once, possibly starving others in the process.  -1 behaves like multi_accept yes in nginx; while 0 (the default) is multi_accept no in nginx.  Positive values allow fine-tuning without the runaway behavior of -1.

This may be specified on a per-listener basis via the multi-accept= per-listener directive (e.g. -l

Default: 0


Most of our signal handling behavior is copied from nginx(8) and/or starman(1); so it is possible to reuse common scripts for managing them.


Reopens log files pointed to by --stdout and --stderr options.


Spawn a new process with the intention to replace the running one. See "Upgrading" below.


Reload config files associated with the process. (Note: broken for public-inbox-httpd(1) only in <= 1.6)


Increase the number of running workers processes by one.


Decrease the number of running worker processes by one.


Stop all running worker processes.   SIGHUP or SIGTTIN may be used to restart workers.


Gracefully terminate the running process.

SIGTTOU, SIGTTIN, SIGWINCH all have no effect when worker processes are disabled with -W0 on the command-line.



The default config file, normally "~/.public-inbox/config". See public-inbox-config(5)


Used by systemd (and compatible) installations for socket activation.  See systemd.socket(5) and sd_listen_fds(3).


Pointing this to point to a writable directory enables the use of Inline and Inline::C extensions which may provide platform-specific performance improvements.  Currently, this enables the use of vfork(2) which speeds up subprocess spawning with the Linux kernel.

public-inbox will never enable Inline::C automatically without this environment variable set or ~/.cache/public-inbox/inline-c created by a user. See Inline and Inline::C for more details.


There are two ways to upgrade a running process.

Users of process management systems with socket activation (systemd(1) or similar) may rely on multiple instances For systemd, this means using two (or more) '@' instances for each service (e.g. SERVICENAME@INSTANCE) as documented in systemd.unit(5).

Users of traditional SysV init may use SIGUSR2 to spawn a replacement process and gracefully terminate the old process using SIGQUIT.

In either case, the old process will not truncate running responses; so responses to expensive requests do not get interrupted and lost.


Feedback welcome via plain-text mail to <mailto:meta@public-inbox.org>

The mail archives are hosted at <https://public-inbox.org/meta/> and <http://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/meta/>

See Also

public-inbox-httpd(1), public-inbox-imapd(1), public-inbox-nntpd(1), public-inbox-pop3d(1), public-inbox-netd(1)

Referenced By

lei-daemon(8), lei-security(7), public-inbox.cgi(1), public-inbox-config(5), public-inbox-httpd(1), public-inbox-imapd(1), public-inbox-netd(1), public-inbox-nntpd(1), public-inbox-pop3d(1), public-inbox-tuning(7), public-inbox-watch(1).

1993-10-02 public-inbox.git public-inbox user manual