You can download gifsicle from
https://www.lcdf.org/gifsicle/
To install gifsicle, run
cd /usr/local/src wget https://www.lcdf.org/gifsicle/gifsicle-1.92.tar.gz tar xvf gifsicle-1.92.tar.gz cd gifsicle-1.92 ./configure make make install
Gifsicle binary file will be installed at
/usr/local/bin/gifsicle