Spaces in filename for ffmpeg in bash [duplicate] - bash

Question

This question already has answers here:
When to wrap quotes around a shell variable?
(5 answers)
Closed 6 years ago.
I try to write a simple transcoding script for VHS backups with ffmpeg. But I fail to handle spaces in filenames.
I build my ffmpeg command together in the script and echo it and when I copy paste the echoed command it works, but not diretcly from the script.
Has anayone a idea whats wrong with my script?
Script:
#!/bin/bash
# VHStoMP4Backup Script
INPUT=$1
OUTPUT="/Volumes/Data/oliver/Video/Encodiert/${2}"
command="ffmpeg \
-i \"$INPUT\" \
-vcodec copy \
-acodec copy \
\"$OUTPUT\""
if [ ! -z "$1" ] && [ ! -z "$2" ] ;
then
echo ${command}$'\n'
${command}
else
echo "missing parameters"
echo "Usage: script INPUT_FILENAME OUTPUT_FILENAME"
fi
exit
Script calling:
./VHStoMP4Backup.sh /Volumes/Data/oliver/Video/RAW\ Aufnahmen/Ewelina\ -\ Kasette\ 1.dv ewe.mp4
Commandline output
olivers-mac-pro:Desktop oliver$ ./VHStoMP4Backup.sh /Volumes/Data/oliver/Video/RAW\ Aufnahmen/Ewelina\ -\ Kasette\ 1.dv ewe.mp4
ffmpeg -i "/Volumes/Data/oliver/Video/RAW Aufnahmen/Ewelina - Kasette 1.dv" -vcodec copy -acodec copy "/Volumes/Data/oliver/Video/Encodiert/ewe.mp4"
ffmpeg version git-2016-04-16-60517c3 Copyright (c) 2000-2016 the FFmpeg developers
built with Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx --enable-librtmp --enable-libfaac --enable-libass --enable-libssh --enable-libspeex --enable-libfdk-aac --enable-openssl --enable-libopus --enable-libvidstab --enable-libx265 --enable-nonfree --enable-vda
libavutil 55. 22.100 / 55. 22.100
libavcodec 57. 34.102 / 57. 34.102
libavformat 57. 34.101 / 57. 34.101
libavdevice 57. 0.101 / 57. 0.101
libavfilter 6. 42.100 / 6. 42.100
libavresample 3. 0. 0 / 3. 0. 0
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
"/Volumes/Data/oliver/Video/RAW: No such file or directory

Answer 1

Never store a command and its arguments in a regular variable, expecting to execute the command simply by expanding the variable.
Use an array to store the arguments, then expand the array when you call the actual command.
if [ $# -lt 3 ]; then
echo "missing parameters"
echo "Usage: script INPUT_FILENAME OUTPUT_FILENAME"
else
INPUT=$1
OUTPUT="/Volumes/Data/oliver/Video/Encodiert/${2}"
args=( -i "$INPUT" -vcodec -acodec "$OUTPUT" )
ffmpeg "${args[#]}"
fi
You need to do a little more work to log the command properly, but that is a small price to pay for safe, correct code.
printf 'ffmpeg'
printf ' %q' "${args[#]}"
printf '\n'
(The logged command won't look exactly like you expect, but it can be used as a valid command line to run the same command. In particular, the %q specifier tends to escape characters individually with a backslash instead of putting longer strings in quotes.)