Bash script to trim last few seconds of video files (.mp4) downloaded with you-get using ffmpeg

TrimLast18s

#!/bin/bash
for f in *.mp4; do
    duration=$(ffmpeg -i "$f" 2>&1 | grep "Duration"| cut -d ' ' -f 4 | sed s/,//)
    length=$(echo "$duration" | awk '{ split($1, A, ":"); print 3600*A[1] + 60*A[2] + A[3] }' )
    trim_start=0
    trim_end=$(echo "$length" - 18 - "$trim_start" | bc)
    ffmpeg -ss "$trim_start" -i "$f" -c copy -map 0 -t "$trim_end" "${f%.mp4}-trimmed.mp4"
done

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