Summary and Info:
probably something in the post_install cat routine set it off. But it still shouldn't segfault, should it?

(Archx86_64, pacman 3.0.6-1 antiword 0.37-1)
What more info do you need?
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[snip]
(1/1) Installiere antiword [#############################################################################] 100%
NOTES On Antiword Integration:

* If you use mozplugger, make sure to configure the
msword section like so (replacing <TERMINAL> with your
terminal of choice):
application/msword: doc, dot: Microsoft Word Document
ignore_errors exits: antiword-helper <TERMINAL> ""

* To properly use antiword in your mailcap settings:
Internal pacman error: Segmentation fault
Please submit a full bug report, with the given package if appropriate.
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[wagner@apollo Dokumente]$ less /var/abs/extra/office/antiword/antiword.install
post_install()
{
cat << EOF
NOTES On Antiword Integration:

* If you use mozplugger, make sure to configure the
msword section like so (replacing <TERMINAL> with your
terminal of choice):
application/msword: doc, dot: Microsoft Word Document
ignore_errors exits: antiword-helper <TERMINAL> "$file"

* To properly use antiword in your mailcap settings:
application/msword; antiword %s; copiousoutput

* To enable drag-and-drop support in KDE, use the kantiword script
EOF
}

post_upgrade()
{
post_install $1
}

op=$1
shift
$op $*
-----------

Steps to Reproduce:

sudo pacman -S antiword