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lei-daemon - Man Page

technical information for local email interface daemon


This documentation is a high-level overview for developers and administrators interested in how lei works.

lei-daemon is a background daemon which powers the lei(1) command-line tool.  It may support virtual users and read-write IMAP+JMAP APIs in the future.  It is designed to optimize shell completion by avoiding module loading costs, monitor Maildirs (and in the near future, IMAP folders) for changes.

worker processes

Most commands cause lei-daemon to fork(2) new worker processes to isolate and parallelize work.  lei-daemon is significantly more aggressive than read-only public-inbox-daemon(8) processes with regards to resource use since it's not designed to support C10K/C100K scenarios.

file descriptor passing

FD passing is used to reduce IPC costs for bulk I/O when importing large mboxes from stdin and dumping large mboxes to stdout.


SOCK_SEQPACKET sockets are used for both communicating with lei(1) and to internal workers.  SOCK_SEQPACKET guarantees reliability (unlike SOCK_DGRAM), allows easy load distribution, and saves developers the trouble of maintaining stream parsers.

file monitoring

Inotify or EVFILT_VNODE is used depending on the platform to monitor Maildirs for changes and track keyword changes.

The listen socket (default: $XDG_RUNTIME_DIR/lei/5.seq.sock) is also monitored, and the daemon will automatically shutdown if it is unlinked.


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

lei-overview(7), lei-daemon-kill(1), lei-daemon-pid(1)

Referenced By

lei(1), lei-add-watch(1), lei-daemon-kill(1), lei-store-format(5).

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