remove test files

tmp.sh

-#!/bin/busybox ash
-set -euo pipefail
-
-rm tmp.mkv || true
-
-ffmpeg -hide_banner \
-	-loop 1 -r 25 -t 3 -i question.png \
-	-filter_complex "
-		gradients=s=2560x1440:d=5:c0=#000055:c1=#005500:x0=480:y0=540:x1=1440:y1=540[input];
-		[0]fade=t=in:st=1:d=0.5:alpha=1,fade=t=out:st=2.5:d=0.5:alpha=1,setpts=PTS+1/TB[overlay];
-		[input][overlay]overlay=eval=frame:x=0:y=0:repeatlast=0[v]
-	" \
-	-map "[v]" \
-	-c:v libsvtav1 -preset 1 -crf 18 \
-	"tmp.mkv"