Often you may want to find all files that exist in one directory but not in another directory in Bash.
You can use the following syntax to do so:
diff -r $dir1 $dir2 | grep $dir1 | awk '{ print $4 }'
This particular example will return all files that exist in the directory specified by the $dir1 variable but not in the directory specified by the $dir2 variable.
Here is what the various commands do:
- diff -r: Recursively return differences between the two directories
- grep $dir1: Only display lines in output that contain the path specified by $dir1
- awk ‘{ print $4 }’ : Only print the fourth column in the output, which contains the filename only
The following example shows how to use this syntax in practice.
Example: Find Files that Exist in One Directory But Not in Another in Bash
Suppose that we have the following two directories on our computer:
- c:/users/bobbi/old_data
- c:/users/bobbi/new_data
Suppose that we would like to find all files that exist in the old_data directory but not in the new_data directory.
We can use the following syntax to first view the filenames in each directory:
dir1="c:/users/bobbi/old_data" dir2="c:/users/bobbi/new_data" ls $dir1 ls $dir2
The following screenshot shows how to use this syntax in practice:
We can then use the following syntax to find the files that only exist in the old_data directory and not in the new_data directory:
diff -r $dir1 $dir2 | grep $dir1 | awk '{ print $4 }'
The following screenshot shows how to use this syntax in practice:
Notice that this returns the following two filenames:
- coaches.xlsx
- owners.xlsx
By viewing the output from the ls commands, we can confirm that these two files exist only in the old_data directory and not in the new_data directory.
If you’d like, you can also use the > command to save the names of these files to a new file:
diff -r $dir1 $dir2 | grep $dir1 | awk '{ print $4 }' > only_old_data.txt
This particular example will find all filenames that exist in the old_data directory and not the new_data directory, then save the results to a new file named only_old_data.txt.
Related Tutorials
The following tutorials explain how to perform other common tasks in Bash:
Bash: How to List All Files in Folder by Date
Bash: How to List All Files in Folder by Size
Bash: How to Delete All Files in Directory
