How to convert photos saved as iPhone digital photo format (.HEIC) to .JPEG on Ubuntu

Install the required library and other dependency with this code

sudo apt-get install libheif1 libheif-examples

Point the commandline to the related directory with .HEIC extensioned photo files

cd {$into_the_directory_which_contains_photo_files}

Save exported versions of .HEIC photos to .JPEG ones in the directory with this command

for file in *.HEIC; do heif-convert $file ${file/%.HEIC/.jpg}; done

ref: Askubuntu