.\"	@(MHWARNING).\" @(#)$Id: mhn.rf,v 1.14 1993/10/26 20:12:56 jromine Exp $.SC MHN 1.NAmhn \- multi-media MH.SYmhn\%[\%[+folder] \%[msgs] | \%[\-file\0file]].br\%[\-part\0number]... \%[\-type\0content]....br\%[\-list\0\%[\-headers]\0\%[\-noheaders].br       \%[\-realsize]\0\%[\-norealsize]] \%[-nolist].br\%[\-show\0\%[\-serialonly]\0\%[\-noserialonly].br       \%[\-form\0formfile]\0\%[\-pause]\0\%[\-nopause]] \%[\-noshow].br\%[\-store\0\%[\-auto]\0\%[\-noauto]] \%[\-nostore].br\%[\-cache] \%[\-nocache] \%[\-rcache\0policy] \%[\-wcache\0policy].br\%[\-check]\0\%[\-nocheck].br\%[\-ebcdicsafe]\0\%[\-noebcdicsafe].br\%[\-rfc934mode]\0\%[\-norfc934mode].br\%[\-verbose]\0\%[\-noverbose].br\%[\-help].DEThe \fImhn\fR command manipulates multi-media messages as specified inRFC 1521.Four action switches direct the operation of \fImhn\fR,namely `\-list', `\-show', `\-store', and `-cache'.Any of these switches may be used concurrently.Normally these action switches will operate on the content of each of thenamed messages.However,by using the `\-part' and `\-type' switches,the scope of the operation can be focused on particularsubparts (of a multipart content) and/or particular content types.A part specification consists of a series of numbers separated by dots.For example,in a multipart content containing three parts,these would be named as 1, 2, and 3, respectively.If part 2 was also a multipart content containing two parts,these would be named as 2.1 and 2.2, respectively.Note that the `\-part' switch is effective for only messagescontaining a multipart content.If a message has some other kind of content,or if the part is itself another multipart content,the `\-part' switch will not prevent the content from being acted upon.A content specification consists of a content type and a subtype.The initial list of \*(lqstandard\*(rq content types and subtypes can be foundin RFC 1521..ne 18A list of commonly used contents is briefly reproduced here:.sp.nf.in +.5i.ta \w'application  'uType	Subtypes----	--------text	plainmultipart	mixed, alternative, digest, parallelmessage	rfc822, partial, external-bodyapplication	octet-stream, postscriptimage	jpeg, gif, x-pbm, x-pgm, x-ppm, x-xwdaudio	basicvideo	mpeg.re.in -.5i.fi.spSubtypes are mandatory..PPTo specify a content,regardless of its subtype,just use the name of the content,e.g.,\*(lqaudio\*(rq.To specify a specific subtype,separate the two with a slash,e.g.,\*(lqaudio/basic\*(rq.Note that regardless of the values given to the `\-type' switch,a multipart content (of any subtype listed above) is always acted upon.Further note that if the `\-type' switch is used,and it is desirable to act on a message/external-body content,then the `\-type' switch must be used twice:once for message/external-body and once for the content externally referenced.Each content may optionally have an integrity check associated with it.If present and the `-check' switch is given,then \fImhn\fR will attempt to verify the integrity of the content.The option `\-file\ file' directs \fImhn\fR to use the specifiedfile as the source message, rather than a message froma folder.Note that the file should be a validly formatted message,just like any other \fIMH\fR message.It should \fBNOT\fR be in mail drop format(to convert a file in mail drop format to a folder of \fIMH\fR messages,see \fIinc\fR\0(1))..Uh "Listing the Contents"The `\-list' switch tells \fImhn\fR to list the table of contentsassociated with the named messages.The `\-headers' switch indicates that a one-line banner should bedisplayed above the listing.The `\-realsize' switch tells \fImhn\fR to evaluate the \*(lqnative\*(rq(decoded) format of each content prior to listing.This provides an accurate count at the expense of a small delay..Uh "Showing the Contents"The `\-show' switch tells \fImhn\fR to display the contents of the namedmessages.The headers of the message are displayed with the \fImhlproc\fR,using format file \fImhl.headers\fR.(The choice of format file can be overridden by the `\-form\0formfile' switch.)\fImhn\fR will look for information in the user's profile to determinehow the different contents should be displayed.This is accomplished by consulting a display string,and executing it under \fB/bin/sh\fR,with the standard input set to the content..ne 16The display string may contain these escapes:.sp.nf.in +.5i.ta \w'%F  'u%a	additional arguments%e	exclusive execution%f	filename containing content%F	%e, %f, and stdin is terminal not content%l	display listing prior to displaying content%p	%l, and ask for confirmation%s	subtype%d	content description.re.in -.5i.fi.spFor those display strings containing the e- or F-escape,\fImhn\fR will execute at most one of these at any given time.Although the F-escape expands to be the filename containing the content,the e-escape has no expansion as far as the shell is concerned.When the p-escape prompts for confirmation,typing INTR (usually control-C) will tell \fImhn\fR not to displaythat content.(The p-escape can be disabled by specifying `\-nopause'.)Further,when \fImhn\fR is display a content,typing QUIT (usually control-\\) will tell \fImhn\fR to wrap things upimmediately.Note that if the content being displayed is multipart,but not one of the subtypes listed above,then the f- and F-escapes expand to multiple filenames,one for each subordinate content.Further,stdin is not redirected from the terminal to the content.First,\fImhn\fR will look for an entry of the form:.sp.in +.5imhn-show-<type>/<subtype>.in -.5i.spto determine the command to use to display the content.If this isn't found,\fImhn\fR will look for an entry of the form:.sp.in +.5imhn-show-<type>.in -.5i.spto determine the display command..ne 10If this isn't found,\fImhn\fR has two default values:.sp.nf.in +.5imhn-show-text/plain: %pmoreproc '%F'mhn-show-message/rfc822: %pshow -file '%F'.in -.5i.fi.spIf neither apply,\fImhn\fR will check to see if the message has a application/octet-streamcontent with parameter \*(lqtype=tar\*(rq.If so,\fImhn\fR will use an appropriate command.If not,\fImhn\fR will complain..ne 10Example entries might be:.sp.nf.in +.5imhn-show-audio/basic: raw2audio 2>/dev/null | playmhn-show-image: xv '%f'mhn-show-application/PostScript: lpr -Pps.in -.5i.fi.spNote that when using the f- or F-escape,it's a good idea to use single-quotes around the escape.This prevents misinterpretation by the shell of any funny charactersthat might be present in the filename.Because the text content might be in a non-ASCII character set,when \fImhn\fR encounters a \*(lqcharset\*(rq parameter for this content,it checks to see whether the environment variable $MM_CHARSET is setand whether the value of this environment variable is equal to the value ofthe charset parameter.If not,then\fImhn\fR will look for an entry of the form:.sp.in +.5imhn-charset-<charset>.in -.5i.spwhich should contain a command creating an environment to render thecharacter set.This command string should containing a single \*(lq%s\*(rq,which will be filled-in with the command to display the content.An example entry might be:.sp.in +.5imhn-charset-iso-8859-1: xterm -fn '-*-*-medium-r-normal-*-*-120-*-*-c-*-iso8859-*' -e %s.in -.5i.spNote that many pagination programs strip off the high-order bit.However,newer releases of the \fIless\fR program have modest support forsingle-octet character sets.The source to \fIless\fR version 177,which has such support,is found in the MH source tree under \fBmiscellany/less-177\fR.In order to view messages sent in the ISO 8859/1 character set using\fIless\fR,.ne 9put these lines in your \&.login file:.sp.nf.in +.5isetenv LESSCHARSET latin1setenv LESS "-f".in -.5i.fi.spThe first line tells \fIless\fR to use 8859/1 definition for determingwhether a character is \*(lqnormal\*(rq, \*(lqcontrol\*(lq, or\*(lqbinary\*(rq.The second line tells \fIless\fR not to warn you if it encounters afile that has non-ASCII characters.Then,simply set the \fBmoreproc\fR profile entry to \fIless\fR,and it will get called automatically.(To handle other single-octet character sets,look at the \fIless\fR\0(1) manual entry for information about the\fBLESSCHARDEF\fR environment variable.)Finally,\fImhn\fR will process each message serially\0--\0it won't start showingthe next message until all the commands executed to display thecurrent message have terminated.In the case of a multipart content (of any subtype listed above),the content contains advice indicating if the parts should bedisplayed serially or in parallel.Because this may cause confusion,particularly on uni-window displays,the `\-serialonly' switch can be given to tell \fImhn\fR to neverdisplay parts in parallel..Uh "Storing the Contents"The `\-store' switch tells \fImhn\fR to store the contents of thenamed messages in \*(lqnative\*(rq (decoded) format.Two things must be determined:the directory to store the content,and the filenames.Files are written in the directory given by the \fBmhn-storage\fRprofile entry,.ne 6e.g.,.sp.in +.5imhn-storage: /tmp.in -.5i.spIf this entry isn't present,the current working directory is used.\fImhn\fR will look for information in the user's profile to determinehow the different contents should be stored.This is achieved through the use of a formatting string,.ne 13which may contain these escapes:.sp.nf.in +.5i.ta \w'%P  'u%m	message number%P	.part%p	part%s	subtype.re.in -.5i.fi.spIf the content isn't part of a multipart (of any subtype listed above) content,the p-escapes are ignored.Note that if the formatting string starts with a \*(lq+\*(rq character,then these escapes are ignored,and the content is stored in the named folder.(A formatting string consisting solely of a \*(lq+\*(rq characterindicates the current folder.)Further,a formatting string consisting solely of a \*(lq-\*(rq characterindicates the standard-output.First,\fImhn\fR will look for an entry of the form:.sp.in +.5imhn-store-<type>/<subtype>.in -.5i.spto determine the formatting string.If this isn't found,\fImhn\fR will look for an entry of the form:.sp.in +.5imhn-store-<type>.in -.5i.spto determine the formatting string.If this isn't found,\fImhn\fR will check to see if the content is application/octet-streamwith parameter \*(lqtype=tar\*(rq.If so,\fImhn\fR will choose an appropriate filename.If the content is not application/octet-stream,then \fImhn\fR will check to see if the content is a message.If so,\fImhn\fR will use the value \*(lq+\*(rq.If not,\fImhn\fR will use the value \*(lq%m%P.%s\*(rq.Note that if the formatting string starts with a '/',then content will be stored in the full path given(rather than using the value of \fBmhn-storage\fR or the current workingdirectory.)Similarly,if the formatting string starts with a '|',then \fImhn\fR will execute a command which should ultimately storethe content.Note that before executing the command,\fImhn\fR will change to the appropriate directory.Also note that if the formatting string starts with a '|',then \fImhn\fR will also honor the a-escape when processing theformatting string..ne 10Example entries might be:.sp.nf.in +.5imhn-store-text: %m%P.txtmhn-store-audio/basic: | raw2audio -e ulaw -s 8000 -c 1 > %m%P.aumhn-store-application/PostScript: %m%P.ps.in -.5i.fi.spFurther,note that when asked to store a content containing a partial message,\fImhn\fR will try to locate all of the portions and combine them accordingly.Thus,