"mmencode"
The mmencode utility (sometimes called mimencode) can be
used to encode binary files for transmission through email
systems. It is useful in the context of writing shell
scripts, but not so much for direct use by people typing
on the command line. If you have a bunch of images and
would like to create MIME-encoded email messages from
them and send those messages, then the combination of
mmencode and some sendmail chicanery in a shell script
will work nicely.
I had a bit of trouble finding mmencode on my systems
(at least, a version I trusted that wasn't wrapped by
a gigantic Big Brother script - long story), so I ran
around the web for a few minutes and found a copy of
'metamail'. Buried in the guts of the metamail code
is a nice little implementation of mmencode.
So, the first thing you need to do is download the
mmencode.zip file (7950 bytes)
and unzip it in a work directory on your system. This
little zip file contains five files: Makefile, compile-it,
config.h, codes.c, and mmencode.c
Edit the compile-it script to suit your environment; it's
a tiny wrapper script that sets your $PATH so that you pick
up the correct C compiler. If your environment is set up
properly, you may not even need the compile-it script.
Then, just execute the compile-it script. It will build
codes.o and mmencode.o and then build the mmencode binary.
Now, you're ready to send an image file through the mail
via sendmail. Here's a nasty, ugly script for that:
<![CDATA[
#!/bin/ksh
#
# Try to dummy up a mime-encoded mail message
# containing an image
IMAGE=${HOME}/images/biketroop.jpg
MMENCODE=/ora01/home/devel/sandbox/mmencode
MAILBODY=mailbody.txt
# command-line options for mmencode:
#
# b - base64
# q - quoted-printable
# u - decode stdin
# p - newline convention (used only with -b)
${MMENCODE} -b ${IMAGE} -o mmencode.out
# Construct the mail message
cat <<EOF > ${MAILBODY}
From: Colonel Flagg <colonel.flagg@cid.com>
Subject: No One Sees The Wind
Sender: colonel.flagg@cid.com
MIME-version: 1.0
Content-type: multipart/mixed; boundary="Boundary_(ID_wxHPRiM1ebsu1CJ5f3/XqA)"
This is a multi-part message in MIME format.
--Boundary_(ID_wxHPRiM1ebsu1CJ5f3/XqA)
Content-type: text/plain; charset=us-ascii
Content-transfer-encoding: 7BIT
Let's see how this looks.
--Boundary_(ID_wxHPRiM1ebsu1CJ5f3/XqA)
Content-type: image/jpeg; name=biketroop.jpg
Content-transfer-encoding: BASE64
Content-disposition: inline; filename=biketroop.jpg
EOF
cat mmencode.out >> ${MAILBODY}
cat <<EOF >> ${MAILBODY}
--Boundary_(ID_wxHPRiM1ebsu1CJ5f3/XqA)--
EOF
cat ${MAILBODY} | /usr/lib/sendmail target.address@anywhere.com
]]>
I warned you, didn't I? That script is the most mud-ugly,
brute-force way imaginable to create a mail message that
has both a normal text portion and a MIME-encoded image
attachment. The script first runs mmencode to encode the
image file into a text file ('mmencode.out') and then
uses 'cat' to cram a bunch of text and email headers
around it.
By the way, you may have noticed that this approach lets you
fake some key bits of data - like the sender's name, that
sort of thing. Don't get too carried away, though, because
sendmail and the networking software is probably smarter
than you think. Use your powers for good, Grasshopper.
Ta-da!
Note: this is in your bin directory (binary and shell script and sample image) - and
it works to send images in email to gmail inboxes!
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