trim mp3 files using ffmpeg, works for video too

ffprobe.exe to get duration of MP3 in number of seconds.
   ffprobe  -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 file.mp3

ffmpeg.exe to trim away first 8 seconds, end at 999 seconds of All mp3 files in the working folder.
  ffmpeg.exe -ss 8 -t   999  -i input.mp3 -acodec copy output.mp3

Trim from 00:02:54.583 to end of file:
 ffmpeg  -ss 00:02:54.583 -i input.mp3 -acodec copy output.mp3

Works for video too:
ffmpeg -ss [start] -i in.mp4 -t [duration] -c copy out.mp4
ffmpeg -ss [start] -i in.mp4 -t [duration] -c:v libx264 -c:a aac -strict experimental -b:a 128k out.mp4


C:\ffmpeg Folder\mp3files\go.bat

echo "==========" > done.txt
for %%f in (*.mp3) do  (
    echo|set /p="..\ffmpeg.exe                         %%f                           " >> done.txt   
  ..\ffprobe  -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1  %%f  >> done.txt
)
rem Open done.txt in Excel, deduct 18 from the -t seconds     

rem (objective is to cut first 8 seconds, trim last 10 seconds of each mp3) 

rem use =concate() to reconstruct the command list, to put to new.bat
rem rearrange param, -ss and -t must precede -i