Convert cbr files to PDF files

Makefile

src_dir = sources
dist_dir = dist
cbr_files = $(wildcard $(src_dir)/*.cbr)
pdf_files = $(cbr_files:$(src_dir)/%.cbr=$(dist_dir)/%.pdf)
image_dir = .images-$<

all: ${pdf_files} | $(dist_dir)
	@echo Done

clean:
	rm -rf $(dist_dir)

$(dist_dir):
	mkdir -p $@

$(dist_dir)/%.pdf : $(src_dir)/%.cbr | $(dist_dir)
	@# use @ to prevent `make` from printing the command it is executing
	@echo Building $< into $@
	@#              ^      ^
	@#              |      |
	@#              |      |
	@#              |      +- foo.pdf
	@#              |
	@#              +- foo.cbr
	@#
	rar x $< ${image_dir}/
	@#  ^  ^     ^
	@#  |  |     |
	@#  |  |     +- unpack to destination directory
	@#  |  |
	@#  |  +- foo.cbr
	@#  |
	@#  +- extract
	@#
	find ${image_dir}/ -size 0 -ls -delete
	@#        ^           ^     ^     ^
	@#        |           |     |     |
	@#        |           |     |     +- delete the file
	@#        |           |     |
	@#        |           |     +- print `ls -l` of the file
	@#        |           |
	@#        |           +- only files with zero size
	@#        +- find in image directory
	@#
	magick convert ${image_dir}/* $@
	@#                  ^          ^
	@#                  |          |
	@#                  |          +- foo.pdf
	@#                  |
	@#                  +- all files in image directory
	@#
	rm -rf ${image_dir}
	@#          ^
	@#          |
	@#          +- delete entire image director. We don't need it anymore.
	@#
	@echo $@ is ready

Uses rar, make and convert from imagemagick to unpack cbr files into .images/ and convert them to a pdf.

The Makefile is only a few lines longer than a bash script would be and has the following benefits because of make:

• automatic looping because of wildcard
• simple file extension mapping at #2
• stops on errors without remembering bash flag -e
• make will only create new and changed cbr files
• make -j 4 provides parallel processing! Change 4 to the number of cores minus 1.

cd /path/to/cbr_files
curl -O https://gist.githubusercontent.com/ddrscott/bf786c589d8feeaf5dfc9546008de1ad/raw/c578ec960c7514dbd895dde5eabe2c0e11407f5c/MakefileMakefile
make