Gif terminal manipulation

Old way to cut out every other frame (requires you manually find frame count):

gifsicle input_file.gif `seq -f "#%g" 0 2 273` --unoptimize -O2 -o output_file.gif

Alternative, easier to put in bashrc (via), e.g. to halve frames (not necessarily half filesize):

gif_framecount_reducer input.gif 2

appends _reduced_x2 to filename

function gif_framecount_reducer () {
        # args: $gif_path $frames_reduction_factor
        local orig_gif="${1?'Missing GIF filename parameter'}"
        local reduction_factor=${2?'Missing reduction factor parameter'}
        # Extracting the delays between each frames
        local orig_delay=$(gifsicle -I "$orig_gif" | sed -ne 's/.*delay \([0-9.]\+\)s/\1/p' | uniq)
        # Ensuring this delay is constant
        [ $(echo "$orig_delay" | wc -l) -ne 1 ] \
                && echo "Input GIF doesn't have a fixed framerate" >&2 \
                && return 1
        # Computing the current and new FPS
        local new_fps=$(echo "(1/$orig_delay)/$reduction_factor" | bc)
        # Exploding the animation into individual images in /var/tmp
        local tmp_frames_prefix="/var/tmp/${orig_gif%.*}_"
        convert "$orig_gif" -coalesce +adjoin "$tmp_frames_prefix%05d.gif"
        local frames_count=$(ls "$tmp_frames_prefix"*.gif | wc -l)
        # Creating a symlink for one frame every $reduction_factor
        local sel_frames_prefix="/var/tmp/sel_${orig_gif%.*}_"
        for i in $(seq 0 $reduction_factor $((frames_count-1))); do
                local suffix=$(printf "%05d.gif" $i)
                ln -s "$tmp_frames_prefix$suffix" "$sel_frames_prefix$suffix"
        done
        # Assembling the new animated GIF from the selected frames
        convert -delay $new_fps "$sel_frames_prefix"*.gif "${orig_gif%.*}_reduced_x${reduction_factor}.gif"
        # Cleaning up
        rm "$tmp_frames_prefix"*.gif "$sel_frames_prefix"*.gif
}

Replace /usr/bin/gifsicle with new release (static binary) via current GitHub release: 1.82.1

gifsicle -O3 --lossy=30 -o output.gif input_reduced_x2.gif

Unlike the hosted service at ezgif.com/optimize (which is great!), can use any value for the --lossy flag.