[SOLVED] How to compare folders size in bash/sh?

Issue

I am building a simple caching script in bash.

Let us assume we have the folders

• source
• dest

I want to write a if condition and check if the total size of source matches the total size of dest (by total size I mean it includes also the subfolders subfiles recursively everything), then do some action.

The script will look something like:

sourceSizeInBytes=2; // dont know how to get only total in bytes
destSizeInBytes=2; // dont know how to get only total in bytes

if [ $sourceSizeInBytes -eq $destSizeInBytes ]
then
   echo "Both folders have equal size. I will do something";
else
  echo "folders are not of the same size";
fi

du -sch gives not just a number but more information.

How can I write such a condition in one reliable way ?

Solution

As suggested by @Charles Duffy in the comments, if you're using GNU bash, below code is more suitable:

read sourceSizeInBytes _ < <(du -s --bytes source) 
read destSizeInBytes _ < <(du -s --bytes dest) 
   
if (( sourceSizeInBytes == destSizeInBytes ))
then
   echo "Both folders have equal size. I will do something"
else
  echo "folders are not of the same size"
fi

Answered By - ashish_k

Answer Checked By - Cary Denson (WPSolving Admin)