[Linux] Delete/Remove files before certain days with certain extension

1. Find files under current directory (maximum 4 subdirectories) at least 1 day ago | select files with ‘.bam’ | select files with ‘variant’ | output file list to variant_bam_removed.txt

find ./ -maxdepth 4 -mtime +1 | grep '.bam' | grep 'variant' > variant_bam_removed.txt

2. Remove files using input of a file, variant_bam_removed.txt

xargs rm < variant_bam_removed.txt

3. Append current file list to a total list

cat variant_bam_removed.txt >> removed_list.txt