Re: bash command substitution

[Brian Inglis <Brian.Inglis@SystematicSw.ab.ca>]

On 2017-10-01 00:40, Vukovics Mihaly wrote:
> I just wanted to use my bash script written in Debian 8 in cygwin(latest, win10
> 64bit), but does not work.
> At a specific line there is a command substitution trying to get result from
> ffprobe:
> VHEIGHT=$(ffprobe -v error -show_entries stream=width,height -of
> default=noprint_wrappers=1 ${OLDFILE} | grep "height" | cut -f2 -d'=')
> For debugging purpose the same command is executed without putting the result
> into a variable, and works! Does anyone know why is it not working in cygwin?
> Code:
> ...
> declare -i VHEIGHT
> ffprobe -v error -show_entries stream=width,height -of
> default=noprint_wrappers=1 ${OLDFILE} | grep height | cut -f2 -d'='
> VHEIGHT=$(ffprobe -v error -show_entries stream=width,height -of
> default=noprint_wrappers=1 ${OLDFILE} | grep "height" | cut -f2 -d'=')
> ...
> Here is some debug log (set -x):
> ....
> + declare -i VHEIGHT
> + ffprobe -v error -show_entries stream=width,height -of
> default=noprint_wrappers=1 P1220312.MP4
> + grep height
> + cut -f2 -d=
> 2160              # this woudl be the desired value
> + VHEIGHT=        # here the variable is empty!
> + VIDSTABDETECTOPTS=:shakiness=10
> + VIDSTABDETECTOPTS+=:result=P1220312-stab.trf
> + VIDSTABTRANSFORMOPTS+=:crop=keep
> ....
> The same in Linux bash:
> ...
> + declare -i VHEIGHT
> + ffprobe -v error -show_entries stream=width,height -of
> default=noprint_wrappers=1 P1220312.MP4
> + grep height
> + cut -f2 -d=
> 2160
> ++ ffprobe -v error -show_entries stream=width,height -of
> default=noprint_wrappers=1 P1220312.MP4
> ++ grep height
> ++ cut -f2 -d=
> + VHEIGHT=2160     # here is the desired value in the variable!!!
> ...
> Any suggestions?

Non-numeric characters in string - add "| cat -A" to the end of your pipe,
or equivalent od or xxd commands to see what's there.
There is no Cygwin package so how was ffprobe built - with Cygwin or Mingw?
May be extraneous trailing spaces or \r at end of input - try "set -o igncr".

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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