qmail-getpw.9

linux下qmail的源码 本人加了一些注释

.TH qmail-getpw 8
.SH NAME
qmail-getpw \- give addresses to users
.SH SYNOPSIS
.B qmail-getpw
.I local
.SH DESCRIPTION
In
.BR qmail ,
each user controls a vast array of local addresses.
.B qmail-getpw
finds the user that controls a particular address,
.IR local .
It prints six pieces of information,
each terminated by NUL:
.IR user ;
.IR uid ;
.IR gid ;
.IR homedir ;
.IR dash ;
and
.IR ext .
The user's account name is
.IR user ;
the user's uid and gid in decimal are
.I uid
and
.IR gid ;
the user's home directory is
.IR homedir ;
and messages to
.I local
will be handled by
.IR homedir\fB/.qmail\fIdashext .

In case of trouble,
.B qmail-getpw
exits nonzero without printing anything.

.B WARNING:
The operating system's
.B getpwnam
function, which is at the heart of
.BR qmail-getpw ,
is inherently unreliable:
it fails to distinguish between temporary errors and nonexistent users.
Future versions of
.B getpwnam
should return ETXTBSY to indicate temporary errors
and ESRCH to indicate nonexistent users.
.SH "RULES"
.B qmail-getpw
considers an account in
.B /etc/passwd
to be a user if
(1) the account has a nonzero uid,
(2) the account's home directory exists (and is visible to
.BR qmail-getpw ),
and
(3) the account owns its home directory.
.B qmail-getpw
ignores account names containing uppercase letters.
.B qmail-getpw
also assumes that all account names are shorter than 32 characters.

.B qmail-getpw
gives each user
control over the basic
.I user
address and
all addresses of the form
.IR user\fBBREAK\fIanything .
When
.I local
is
.IR user ,
.I dash
and
.I ext
are both empty.
When
.I local
is
.IR user\fBBREAK\fIanything ,
.I dash
is a hyphen and
.I ext
is
.IR anything .
.I user
may appear in any combination of uppercase and lowercase letters
at the front of
.IR local .

A catch-all user,
.BR alias ,
controls all other addresses.
In this case
.I ext
is
.I local
and
.I dash
is a hyphen.

You can override all of
.BR qmail-getpw 's
decisions with the
.B qmail-users
mechanism, which is reliable, highly configurable, and much faster than
.BR qmail-getpw .
.SH "SEE ALSO"
qmail-users(5),
qmail-lspawn(8)