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 ##,##,##	tUse 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.