--- /dev/null
+Name
+----
+
+mimedecode -- decode MIME message
+
+Synopsis
+--------
+
+mimedecode [ -h|--help ] [ -V|--version ] [ -cCDP ] [ -f charset ]
+[ -H|--host=hostname ] [ -d header1[,header2,header3...] ]
+[ -d \*[,-header1,-header2,-header3...] ]
+[ -p header1[,header2,header3,...]:param1[,param2,param3,...] ]
+[ -p \*[,-header1,-header2,-header3,...]:param1[,param2,param3,...] ]
+[ -p header1[,header2,header3,...]:\*[,-param1,-param2,-param3,...] ]
+[ -p \*[,-header1,-header2,-header3,...]:\*[,-param1,-param2,-param3,...] ]
+[ -r header1[,header2,header3...] ] [ -r \*[,-header1,-header2,-header3...] ]
+[ -R header1[,header2,header3,...]:param1[,param2,param3,...] ]
+[ -R \*[,-header1,-header2,-header3,...]:param1[,param2,param3,...] ]
+[ -R header1[,header2,header3,...]:\*[,-param1,-param2,-param3,...] ]
+[ -R \*[,-header1,-header2,-header3,...]:\*[,-param1,-param2,-param3,...] ]
+[ --set-header header:value ] [ --set-param header:param=value ]
+[ -BbeIit mask ] [ --save-headers|body|message mask ] [ -O dest_dir ]
+[ -o output_file ] [input_file [output_file] ]
+
+DESCRIPTION
+-----------
+
+Mail users, especially in non-English countries, often find that mail
+messages arrived in different formats, with different content types, in
+different encodings and charsets. Usually it is good because it allows to
+use an appropriate format/encoding/whatever. Sometimes, though, some
+unification is desirable. For example, one may want to put mail messages
+into an archive, make HTML indices, run search indexer, etc. In such
+situations converting messages to text in one character set and skipping
+some binary attachments is much desirable.
+
+Here is a solution - mimedecode!
+
+This is a program to decode MIME messages. The program expects one input
+file (either on command line or on stdin) which is treated as an RFC822
+message, and decodes to stdout or an output file. If the file is not an
+RFC822 message it is just copied to the output one-to-one. If the file is
+a simple RFC822 message it is decoded as one part. If it is a MIME message
+with multiple parts ("attachments") all non-multipart subparts are
+decoded. Decoding can be controlled by the command-line options.
+
+First, for every part the program removes headers and parameters listed
+with -r and -R options. Then, Subject and Content-Disposition headers (and
+all headers listed with -d and -p options) are examined. If any of those
+exists, they are decoded according to RFC2047. Content-Disposition header
+is not decoded (if it was not listed in option -d) - only its "filename"
+parameter. Encoded header parameters violate the RFC, but widely deployed
+anyway by ignorant coders who never even heard about RFCs. Correct
+parameter encoding specified by RFC2231. This program decodes
+RFC2231-encoded parameters, too.
+
+Then the body of the message (or the current part) is decoded. Decoding
+starts with looking at header Content-Transfer-Encoding. If the header
+specifies non-8bit encoding (usually base64 or quoted-printable), the body
+is converted to 8bit (can be prevented with -B). Then if its content type
+is multipart (multipart/related or multipart/mixed, e.g) every part is
+recursively decoded. If it is not multipart, mailcap database is consulted
+to find a way to convert the body to plain text (can be prevented with
+options -Bbei). (The author has no idea how mailcap can be configured on
+OSes other than POSIX, please don't ask; users can consult an example at
+https://phdru.name/Software/dotfiles/mailcap.html). The decoding process
+uses the first copiousoutput filter it can find. If there are no filters
+the body just passed as is.
+
+Then Content-Type header is consulted for charset. If it is not equal to
+the current locale charset and recoding is allowed (see options -Cc) the
+body text is recoded. Finally message headers and the body are flushed to
+stdout.
+
+Please be reminded that in the following options asterisk is a shell
+metacharacter and should be escaped or quoted. Either write -d \*,-h1,-h2
+or -d '\*,-h1,-h2' or such.
+
+OPTIONS
+-------
+
+-h, -help
+
+ Print brief usage help and exit.
+
+-V, --version
+
+ Print version and exit.
+
+-c
+
+ Recode different character sets in message bodies to the current
+ default charset; this is the default.
+
+-C
+
+ Do not recode character sets in message bodies.
+
+-f charset
+
+ Force this charset to be used for recoding instead of charset from
+ the current locale.
+
+-H hostname, --host=hostname
+
+ Use this hostname in X-MIME-Autoconverted headers instead of the
+ current hostname.
+
+-d header1[,header2,header3...]
+
+ Add the header(s) to a list of headers to decode; initially the
+ list contains headers "From", "To", "Cc", "Reply-To",
+ "Mail-Followup-To" and "Subject".
+
+-d \*[,-header1,-header2,-header3...]
+
+ This variant completely changes headers decoding. First, the list
+ of headers to decode is cleared (as with -D). Then all the headers
+ are decoded except the given list of exceptions (headers listed
+ with '-'). In this mode it would be meaningless to give more than
+ one -d options but the program doesn't enforce the limitation.
+
+-D
+
+ Clear the list of headers to decode (make it empty).
+
+-p header1[,header2,header3,...]:param1[,param2,param3,...]
+
+ Add the parameter(s) to a list of headers parameters to decode;
+ the parameter(s) will be decoded only for the given header(s).
+ Initially the list contains header "Content-Type", parameter
+ "name"; and header "Content-Disposition", parameter "filename".
+
+-p \*[,-header1,-header2,-header3,...]:param1[,param2,param3,...]
+
+ Add the parameter(s) to a list of headers parameters to decode;
+ the parameter(s) will be decoded for all headers except the given
+ ones.
+
+-p header1[,header2,header3,...]:\*[,-param1,-param2,-param3,...]
+
+ Decode all parameters except listed for the given list of headers.
+
+-p \*[,-header1,-header2,-header3,...]:\*[,-param1,-param2,-param3,...]
+
+ Decode all parameters except listed for all headers (except
+ listed).
+
+-P
+
+ Clear the list of headers parameters to decode (make it empty).
+
+-r header1[,header2,header3...]
+
+ Add the header(s) to a list of headers to remove completely;
+ initially the list is empty.
+
+-r \*[,-header1,-header2,-header3...]
+
+ Remove all headers except listed.
+
+-R header1[,header2,header3,...]:param1[,param2,param3,...]
+
+ Add the parameter(s) to a list of headers parameters to remove;
+ the parameter(s) will be removed only for the given header(s).
+ Initially the list is empty.
+
+-R \*[,-header1,-header2,-header3,...]:param1[,param2,param3,...]
+
+-R header1[,header2,header3,...]:\*[,-param1,-param2,-param3,...]
+
+-R \*[,-header1,-header2,-header3,...]:\*[,-param1,-param2,-param3,...]
+
+ Remove listed parameters (or all parameters except listed) from
+ these headers (or from all headers except listed).
+
+--set-header header:value
+
+ The program sets or changes value for the header to the given
+ value (only at the top-level message).
+
+--set-param header:param=value
+
+ The program sets or changes value for the header's parameter to
+ the given value (only at the top-level message). The header must
+ exist.
+
+-B mask
+
+ Append mask to the list of binary content types that will be not
+ content-transfer-decoded (will be left as base64 or such).
+
+-b mask
+
+ Append mask to the list of binary content types; if the message to
+ decode has a part of this type the program
+ content-transfer-decodes (base64 or whatever to 8bit binary) it
+ and outputs the decoded part as is, without any further
+ processing.
+
+-e mask
+
+ Append mask to the list of error content types; if the message to
+ decode has a part of this type the program fails with ValueError.
+
+-I mask
+
+ Append mask to the list of content types to completely ignore.
+ There will be no output - no headers, no body, no warning. For a
+ multipart part the entire subtree is removed.
+
+-i mask
+
+ Append mask to the list of content types to ignore; if the message
+ to decode has a part of this type the program outputs headers but
+ skips the body. Instead a line "Message body of type %s skipped."
+ will be issued.
+
+-t mask
+
+ Append mask to the list of content types to convert to text; if
+ the message to decode has a part of this type the program consults
+ mailcap database, find the first copiousoutput filter and, if any
+ filter is found, converts the part.
+
+--save-headers mask
+
+--save-body mask
+
+--save-message mask
+
+ Append mask to lists of content types to save to files;
+ --save-headers saves only decoded headers of the message (or the
+ current subpart); --save-body saves only decoded body;
+ --save-message saves the entire message or subpart (headers +
+ body).
+
+-O dest_dir
+
+ Set destination directory for the output files; if the directory
+ doesn't exist it will be created. Default is the current
+ directory.
+
+-o output_file
+
+ Save output to the file related to the destination directory from
+ option -O. Also useful in case of redirected stdin:
+
+mimedecode -o output_file < input_file
+cat input_file | mimedecode -o output_file
+
+The 5 list options (-Bbeit) require more explanation. They allow a user to
+control body decoding with great flexibility. Think about said mail
+archive; for example, its maintainer wants to put there only texts,
+convert PDF/Postscript to text, pass HTML and images decoding base64 to
+html but leaving images encoded, and ignore everything else. This is how
+it could be done:
+
+mimedecode -t application/pdf -t application/postscript -t text/plain -b
+text/html -B 'image/\*' -i '\*/\*'
+
+When the program decodes a message (non-MIME or a non-multipart subpart of
+a MIME message), it consults Content-Type header. The content type is
+searched in all 5 lists, in order "text-binary-ignore-error". If found,
+appropriate action is performed. If not found, the program searches the
+same lists for "type/\*" mask (the type of "text/html" is just "text"). If
+found, appropriate action is performed. If not found, the program searches
+the same lists for "\*/\*" mask. If found, appropriate action is performed.
+If not found, the program uses the default action, which is to decode
+everything to text (if mailcap specifies a filter). This algorithm allows
+more specific content types to override less specific: -b image/\* will be
+processed earlier than -B \*/\*.
+
+Options -e/-I/-i can also work with multipart subparts of a MIME message.
+In case of -I/-i the entire subtree of that multipart is removed; with -i
+it's replaced with ignore warning.
+
+Initially all 5 lists are empty, so without any additional parameters the
+program always uses the default decoding (as -t \*/\*).
+
+The 3 save options (--save-headers/body/message) are similar. They make
+the program to save every non-multipart subpart (only headers, or body, or
+the entire subpart: headers + body) that corresponds to the given mask to
+a file. Before saving the message (or the subpart) is decoded according to
+all other options and is placed to the output stream as usual. Filename
+for the file is created using "filename" parameter from the
+Content-Disposition header, or "name" parameter from the Content-Type
+header if one of those exist; a serial counter is prepended to the
+filename to avoid collisions; if there are no name/filename parameters, or
+the name/filename parameters contain forbidden characters (null, slash,
+backslash) the filename is just the serial counter.
+
+If the file doesn't have any extensions (no dots in the value of the
+name/filename parameters, or the name is just the counter) the program
+tries to guess an extension by looking up the content type in mime.types
+files including .mime.types file in the user's home directory (if it
+exists). If the file has an extension the program doesn't try to verify
+that it corresponds to the content type.
+
+The file is saved in the directory set with -O (default is the current
+directory). The save options are proceeded before -e options so the user
+can save the message that causes an error.
+
+ENVIRONMENT
+-----------
+
+LANG
+
+LC_ALL
+
+LC_CTYPE
+
+Define current locale settings. Used to determine current default charset
+(if your Python is properly installed and configured).
+
+BUGS
+----
+
+The program may produce incorrect MIME message. The purpose of the program
+is to decode whatever it is possible to decode, not to produce absolutely
+correct MIME output. The incorrect parts are obvious - decoded
+From/To/Cc/Reply-To/Mail-Followup-To/Subject headers and filenames. Other
+than that output is correct MIME message. The program does not try to
+guess whether the headers are correct. For example, if a message header
+states that charset is iso8859-1, but the body (HTML, for example) is
+actually in utf-8 the program will recode the message with the wrong
+charset.
+
+AUTHOR
+------
+
+Oleg Broytman <phd@phdru.name>
+
+COPYRIGHT
+---------
+
+Copyright (C) 2001-2020 PhiloSoft Design.
+
+LICENSE
+-------
+
+GNU GPL
+
+NO WARRANTIES
+-------------
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+for more details.
+
+SEE ALSO
+--------
+
+mimedecode home page: https://phdru.name/Software/Python/#mimedecode
projects / mimedecode.git / blobdiff