+++ /dev/null
-'\" t
-.\" -*-nroff-*-
-.\"
-.\" Copyright (C) 2000 Thomas Roessler <roessler@does-not-exist.org>
-.\"
-.\" This document is in the public domain and may be distributed and
-.\" changed arbitrarily.
-.\"
-.TH mbox 5 "February 19th, 2002" Unix "User Manuals"
-.\"
-.SH NAME
-mbox \- Format for mail message storage.
-.\"
-.SH DESCRIPTION
-This document describes the format traditionally used by Unix hosts
-to store mail messages locally.
-.B mbox
-files typically reside in the system's mail spool, under various
-names in users' Mail directories, and under the name
-.B mbox
-in users' home directories.
-.PP
-An
-.B mbox
-is a text file containing an arbitrary number of e-mail messages.
-Each message consists of a postmark, followed by an e-mail message
-formatted according to \fBRFC822\fP, \fBRFC2822\fP. The file format
-is line-oriented. Lines are separated by line feed characters (ASCII 10).
-.PP
-A postmark line consists of the four characters "From", followed by
-a space character, followed by the message's envelope sender
-address, followed by whitespace, and followed by a time stamp. This
-line is often called From_ line.
-.PP
-The sender address is expected to be
-.B addr-spec
-as defined in \fBRFC2822\fP 3.4.1. The date is expected to be
-.B date-time
-as output by
-.BR asctime(3) .
-For compatibility reasons with legacy software, two-digit years
-greater than or equal to 70 should be interpreted as the years
-1970+, while two-digit years less than 70 should be interpreted as
-the years 2000-2069. Software reading files in this format should
-also be prepared to accept non-numeric timezone information such as
-"CET DST" for Central European Time, daylight saving time.
-.PP
-Example:
-.IP "" 1
->From example@example.com Fri Jun 23 02:56:55 2000
-.PP
-In order to avoid misinterpretation of lines in message bodies
-which begin with the four characters "From", followed by a space
-character, the mail delivery agent must quote any occurrence
-of "From " at the start of a body line.
-.sp
-There are two different quoting schemes, the first (\fBMBOXO\fP) only
-quotes plain "From " lines in the body by prepending a '>' to the
-line; the second (\fBMBOXRD\fP) also quotes already quoted "From "
-lines by prepending a '>' (i.e. ">From ", ">>From ", ...). The later
-has the advantage that lines like
-.IP "" 1
->From the command line you can use the '\-p' option
-.PP
-aren't dequoted wrongly as a \fBMBOXRD\fP-MDA would turn the line
-into
-.IP "" 1
->>From the command line you can use the '\-p' option
-.PP
-before storing it. Besides \fBMBOXO\fP and \fBMBOXRD\fP there is also
-\fBMBOXCL\fP which is \fBMBOXO\fP with a "Content-Length:"\-field with the
-number of bytes in the message body; some MUAs (like
-.BR mutt (1))
-do automatically transform \fBMBOXO\fP mailboxes into \fBMBOXCL\fP ones when
-ever they write them back as \fBMBOXCL\fP can be read by any \fBMBOXO\fP-MUA
-without any problems.
-.PP
-If the modification-time (usually determined via
-.BR stat (2))
-of a nonempty
-.B mbox
-file is greater than the access-time the file has new mail. Many MUAs
-place a Status: header in each message to indicate which messages have
-already been read.
-.\"
-.SH LOCKING
-Since
-.B mbox
-files are frequently accessed by multiple programs in parallel,
-.B mbox
-files should generally not be accessed without locking.
-.PP
-Three different locking mechanisms (and combinations thereof) are in
-general use:
-.IP "\(bu"
-.BR fcntl (2)
-locking is mostly used on recent, POSIX-compliant systems. Use of
-this locking method is, in particular, advisable if
-.B mbox
-files are accessed through the Network File System (NFS), since it
-seems the only way to reliably invalidate NFS clients' caches.
-.IP "\(bu"
-.BR flock (2)
-locking is mostly used on BSD-based systems.
-.IP "\(bu"
-Dotlocking is used on all kinds of systems. In order to lock an
-.B mbox
-file named \fIfolder\fR, an application first creates a temporary file
-with a unique name in the directory in which the
-\fIfolder\fR resides. The application then tries to use the
-.BR link (2)
-system call to create a hard link named \fIfolder.lock\fR
-to the temporary file. The success of the
-.BR link (2)
-system call should be additionally verified using
-.BR stat (2)
-calls. If the link has succeeded, the mail folder is considered
-dotlocked. The temporary file can then safely be unlinked.
-.IP ""
-In order to release the lock, an application just unlinks the
-\fIfolder.lock\fR file.
-.PP
-If multiple methods are combined, implementors should make sure to
-use the non-blocking variants of the
-.BR fcntl (2)
-and
-.BR flock (2)
-system calls in order to avoid deadlocks.
-.PP
-If multiple methods are combined, an
-.B mbox
-file must not be considered to have been successfully locked before
-all individual locks were obtained. When one of the individual
-locking methods fails, an application should release all locks it
-acquired successfully, and restart the entire locking procedure from
-the beginning, after a suitable delay.
-.PP
-The locking mechanism used on a particular system is a matter of
-local policy, and should be consistently used by all applications
-installed on the system which access
-.B mbox
-files. Failure to do so may result in loss of e-mail data, and in
-corrupted
-.B mbox
-files.
-.\"
-.SH FILES
-.IR /var/spool/mail/$LOGNAME
-.RS
-\fB$LOGNAME\fP's incoming mail folder.
-.RE
-.PP
-.IR $HOME/mbox
-.RS
-user's archived mail messages, in his \fB$HOME\fP directory.
-.RE
-.PP
-.IR $HOME/Mail/
-.RS
-A directory in user's \fB$HOME\fP directory which is commonly used to hold
-.B mbox
-format folders.
-.RE
-.PP
-.\"
-.SH "SEE ALSO"
-.BR mutt (1),
-.BR fcntl (2),
-.BR flock (2),
-.BR link (2),
-.BR stat (2),
-.BR asctime (3),
-.BR maildir (5),
-.BR mmdf (5),
-.BR RFC822 ,
-.BR RFC976 ,
-.BR RFC2822
-.\"
-.SH AUTHOR
-Thomas Roessler <roessler@does-not-exist.org>, Urs Janssen <urs@tin.org>
-.\"
-.SH HISTORY
-The
-.B mbox
-format occurred in Version 6 AT&T Unix.
-.br
-A variant of this format was documented in \fBRFC976\fP.
projects / asd-repo.git / blobdiff