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diff --git a/upstream/debian-bookworm/man5/mbox.5 b/upstream/debian-bookworm/man5/mbox.5 new file mode 100644 index 00000000..740c584d --- /dev/null +++ b/upstream/debian-bookworm/man5/mbox.5 @@ -0,0 +1,187 @@ +'\" 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. |