Computer Science
FORMAIL(1) FORMAIL(1)
NAME
formail - mail (re)formatter
SYNOPSIS
formail [+skip] [-total] [-vbczfrktedqBY] [-p prefix]
[-D maxlen idcache]
[-x headerfield] [-X headerfield]
[-a headerfield] [-A headerfield]
[-i headerfield] [-I headerfield]
[-u headerfield] [-U headerfield]
[-R oldfield newfield]
[-n [maxprocs ]] [-m minfields] [-s [command [arg
...]]]
DESCRIPTION
formail is a filter that can be used to force mail into
mailbox format, perform `From ' escaping, generate auto-
replying headers, do simple header munging/extracting or
split up a mailbox/digest/articles file. The mail/mail-
box/article contents will be expected on stdin.
If formail is supposed to determine the sender of the
mail, but is unable to find any, it will substitute
`foo@bar'.
If formail is started without any command line options, it
will force any mail coming from stdin into mailbox format
and will escape all bogus `From ' lines with a `>'.
OPTIONS
-v Formail will print its version number and exit.
-b Don't escape any bogus mailbox headers (i.e. lines
starting with `From ').
-p prefix
Define a different quotation prefix. If unspecified
it defaults to `>'.
-Y Assume traditional Berkeley mailbox format, ignoring
any Content-Length: fields.
-c Concatenate continued fields in the header. Might be
convenient when postprocessing mail with standard
(line oriented) text utilities.
-z Ensure a whitespace exists between field name and
content. Zap fields which contain only a single
whitespace character. Zap leading and trailing
whitespace on fields extracted with -x.
-f Force formail to simply pass along any non-mailbox
format (i.e. don't generate a `From ' line as the
first line).
-r Generate an auto-reply header. This will normally
throw away all the existing fields (except X-Loop:)
in the original message, fields you wish to preserve
need to be named using the -i option. If you use
this option in conjunction with -k, you can prevent
the body from being `escaped' by also specifying -b.
-k When generating the auto-reply header or when
extracting fields, keep the body as well.
-t Trust the sender to have used a valid return address
in his header. This option will be most useful when
generating auto-reply headers from news articles. If
this option is not turned on, formail tends to favour
machine-generated addresses in the header.
-s The input will be split up into separate mail mes-
sages, and piped into a program one by one (a new
program is started for every part). -s has to be the
last option specified, the first argument following
it is expected to be the name of a program, any other
arguments will be passed along to it. If you omit
the program, then formail will simply concatenate the
splitted mails on stdout again. See FILENO.
-n [maxprocs]
Tell formail not to wait for every program to finish
before starting the next (causes splits to be pro-
cessed in parallel). Maxprocs optionally specifies
an upper limit on the number of concurrently running
processes.
-e Do not require empty lines to be preceding the header
of a new message (i.e. the messages could start on
every line).
-d Tell formail that the messages it is supposed to
split need not be in strict mailbox format (i.e.
allows you to split digests/articles or non-standard
mailbox formats). This disables recognition of the
Content-Length: field.
-B Makes formail assume that it is splitting up a BABYL
rmail file.
-m minfields
Allows you to specify the number of consecutive head-
erfields formail needs to find before it decides it
found the start of a new message, it defaults to 2.
-q Tells formail to (still detect but) be quiet about
write errors, duplicate messages and mismatched Con-
tent-Length: fields. This option is on by default,
to make it display the messages use -q-.
-D maxlen idcache
Formail will detect if the Message-ID of the current
message has already been seen using an idcache file
of approximately maxlen size. If not splitting, it
will return success if a duplicate has been found.
If splitting, it will not output duplicate messages.
If used in conjunction with -r, formail will look at
the mail address of the sender instead at the Mes-
sage-ID.
-x headerfield
Extract the contents of this headerfield from the
header, display it as a single line.
-X headerfield
Same as -x, but also preserves the field name.
-a headerfield
Append a custom headerfield onto the header; but only
if a similar field does not exist yet. If you spec-
ify either one of the field names Message-ID: or
Resent-Message-ID: with no field contents, then for-
mail will generate a unique message-ID for you.
-A headerfield
Append a custom headerfield onto the header in any
case.
-i headerfield
Same as -A, except that any existing similar fields
are renamed by prepending an ``Old-'' prefix. If
headerfield consists only of a field-name, it will
not be appended.
-I headerfield
Same as -i, except that any existing similar fields
are simply removed. If headerfield consists only of
a field-name, it effectively deletes the field.
-u headerfield
Make the first occurrence of this field unique, and
thus delete all subsequent occurrences of it.
-U headerfield
Make the last occurrence of this field unique, and
thus delete all preceding occurrences of it.
-R oldfield newfield
Renames all occurrences of the fieldname oldfield
into newfield.
+skip
Skip the first skip messages while splitting.
-total
Output at most total messages while splitting.
ENVIRONMENT
FILENO
While splitting, formail assigns the message number
currently being output to this variable. By preset-
ting FILENO, you can change the initial message num-
ber being used and the width of the zero-padded out-
put. If FILENO is unset it will default to 000. If
FILENO is non-empty and does not contain a number,
FILENO generation is disabled.
EXAMPLES
To split up a digest one usually uses:
formail +1 -ds >>the_mailbox_of_your_choice
or
formail +1 -ds procmail
To remove all Received: fields from the header:
formail -I Received:
To remove all fields except From: and Subject: from the
header:
formail -k -X From: -X Subject:
To supersede the Reply-To: field in a header you could
use:
formail -i "Reply-To: foo@bar"
To convert a non-standard mailbox file into a standard
mailbox file you can use:
formail -ds <old_mailbox >>new_mailbox
Or, if you have a very tolerant mailer:
formail -a Date: -ds <old_mailbox >>new_mailbox
To extract the header from a message:
formail -X ""
or
sed -e '/^$/ q'
To extract the body from a message:
formail -I ""
or
sed -e '1,/^$/ d'
SEE ALSO
mail(1), binmail(1), sendmail(8), procmail(1), sed(1),
sh(1), RFC822, RFC1123
DIAGNOSTICS
Can't fork Too many processes on this machine.
Content-Length: field exceeds actual length by nnn bytes
The Content-Length: field in the
header specified a length that was
longer than the actual body. This
causes this message to absorb a
number of subsequent messages fol-
lowing it in the same mailbox.
Couldn't write to stdout
The program that formail was trying
to pipe into didn't accept all the
data formail sent to it; this diag-
nostic can be suppressed by the -q
option.
Duplicate key found: x The Message-ID or sender x in this
message was found in the idcache;
this diagnostic can be suppressed
by the -q option.
Failed to execute "x" Program not in path, or not exe-
cutable.
File table full Too many open files on this ma-
chine.
Invalid field-name: "x"
The specified field-name "x" con-
tains control characters, or cannot
be a partial field-name for this
option.
WARNINGS
You can save yourself and others a lot of grief if you try
to avoid using this autoreply feature on mails coming
through mailinglists. Depending on the format of the in-
coming mail (which in turn depends on both the original
sender's mail agent and the mailinglist setup) formail
could decide to generate an autoreply header that replies
to the list.
BUGS
When formail has to generate a leading `From ' line it
normally will contain the current date. If formail is
given the option `-a Date:', it will use the date from the
`Date:' field in the header (if present). However, since
formail copies it verbatim, the format will differ from
that expected by most mail readers.
If formail is instructed to delete or rename the leading
`From ' line, it will not automatically regenerate it as
usual. To force formail to regenerate it in this case,
include -a 'From '.
If formail is not called as the first program in a pipe
and it is told to split up the input in several messages,
then formail will not terminate until the program it re-
ceives the input from terminates itself.
If formail is instructed to generate an autoreply mail, it
will never put more than one address in the `To:' field.
MISCELLANEOUS
Formail is eight-bit clean.
When formail has to determine the sender's address, every
RFC822 conforming mail address is allowed. Formail will
always strip down the address to its minimal form (delet-
ing excessive comments and whitespace).
The regular expression that is used to find `real' post-
marks is:
"\n\nFrom [\t ]*[^\t\n ]+[\t ]+[^\n\t ]"
If a Content-Length: field is found in a header, formail
will copy the number of specified bytes in the body verba-
tim before resuming the regular scanning for message
boundaries (except when splitting digests or Berkeley
mailbox format is assumed).
NOTES
Calling up formail with the -h or -? options will cause it
to display a command-line help page.
SOURCE
This program is part of the procmail mail-processing-pack-
age (v3.13.1) available at http://www.procmail.org/ or
ftp.procmail.org in pub/procmail/.
MAILINGLIST
There exists a mailinglist for questions relating to any
program in the procmail package:
<procmail-users@procmail.org>
for submitting questions/answers.
<procmail-users-request@procmail.org>
for subscription requests.
If you would like to stay informed about new versions and
official patches send a subscription request to
procmail-announce-request@procmail.org
(this is a readonly list).
AUTHOR
Stephen R. van den Berg
<srb@cuci.nl>
BuGless 1999/01/20 1
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