shell scripting no such file or directory - shell

Question

I wrote a shell script that calls the ffmpeg tool but when I run it, it says No such file or directory yet it does!
Here is my script:
#!/bin/bash
MAIN_DIR="/media/sf_data/pipeline"
FFMPEG_DIR="/media/sf_data/livraison_transcripts/ffmpeg-git-20180208-64bit-static"
for file in MAIN_DIR/audio_mp3/*.mp3;
do
cp -p file FFMPEG_DIR;
done
for file in FFMPEG_DIR/*.mp3;
do
./ffmpeg -i ${file%.mp3}.ogg
sox $file -t raw --channels=1 --bits=16 --rate=16000 --encoding=signed-
integer --endian=little ${file%.ogg}.raw;
done
for file in FFMPEG_DIR/*.raw;
do
cp -p file MAIN_DIR/pipeline/audio_raw/;
done
and here is the debug response:
cp: cannot stat ‘file’: No such file or directory
./essai.sh: line 14: ./ffmpeg: No such file or directory
sox FAIL formats: can't open input file `FFMPEG_DIR/*.mp3': No such file or
directory
cp: cannot stat ‘file’: No such file or directory
FYI I'm running CentOS7 on VirtualBox
Thank you

Answer 1

Here's a Minimal, Complete, and Verifiable example (MCVE), a version of your script that removes everything not required to show the problem:
#!/bin/bash
MAIN_DIR="/media/sf_data/pipeline"
echo MAIN_DIR
Expected output:
/media/sf_data/pipeline
Actual output:
MAIN_DIR
This is because bash requires a $ when expanding variables:
#!/bin/bash
MAIN_DIR="/media/sf_data/pipeline"
echo "$MAIN_DIR"
The quotes are not required to fix the issue, but prevent issues with whitespaces.

Answer 2

Hi You need couple of correction in your shell script see below. To get the actual value assigned to a variable you need to add $ at the front of the variable in shell script.
for file in $"MAIN_DIR"/audio_mp3/*.mp3;
do
cp -p "$file" "$FFMPEG_DIR";
done
for file in "$FFMPEG_DIR"/*.mp3;
./ffmpeg -i ${file%.mp3}.ogg
#provide full path like /usr/bin/ffmpeg
for file in "$FFMPEG_DIR"/*.raw;
do
cp -p "$file" "$MAIN_DIR"/pipeline/audio_raw/;
done