GIFTool , a tool for GIF89a trasnparent option  and interlace mode.

Usage: giftool [options] [file]
       giftool (-p|-c|-B) [options] [files...]
	-B	Batch Mode, read and write the same filename
	-i	Set GIF Interlace mode ON
	+i	Set GIF Interlace mode OFF
	-p	Print information about file(s)
	-c	Print comment information
	+c	Add comments to file(s)
	-C	Strip comment from file(s)
	-o file	Send output to 'file'
	-rgb name	Use 'name' as the transparent pixel
	-rgb ##,##,##	Use rgb-value as the transparent pixel
	-###	Used pixel index as transparent (1 == first colormap entry)

For instance you could say 'giftool -B -i *.gif' to convert all your images
to interlaced GIF files in one easy step.

giftool version 1.0 is Copyright 1994 Home Pages, Inc and is shareware.
Please, use the -info option to read the licensing information.

PORT BUILD OPTION
=================

There are two useful options are suggested and available for this port of
giftool. You can specify it following "make clean".

make RETVALUE=yes
-----------
Giftool does not return value from main(), so it is impossible to use this
tools in programs like make(1) or pipes.
This option is suggested by Sergei Chechetkin <csl@whale.sunbay.crimea.ua>.

make MALLOCSIZE=yes
---------------
Giftool 1.0 or some earlier version cause segmentation fault about some
images. Something about pre-read seems to be bad, so make malloc size 
bigger to improve that.
This option is suggested by Hidetoshi Shimokawa <simokawa@sat.t.u-tokyo.ac.jp>.

You can specify all options such as 'make RETVALUE=yes MALLOCSIZE=yes'.