Makefile

An executable notebook or executable cookbook.

• Makefiles have a version check system built in. For example, if you use a makefile to process a set of jpg's, it takes them all. If you run the makefile again, it only processes the files that where changed.
• Makefiles originated on Unix-like systems and are still a primary software build mechanism in such environments. [1]

Links

GNU Make

GNU Make Manual

Wikipedia page on Makefiles

Example makefile

Working with the following structure:

pi@raspberry% tree          
.
├── images
│   ├── 0000.jpg
│   ├── 0001.jpg
│   ├── 0002.jpg
│   └── 0003.jpg
├── Makefile
├── output
│   └── a-new-file.txt
└── src
    ├── list.txt
    ├── plain.txt
    └── myscript.py

Makefile

images=$(wildcard images/*.jpg)
# creates: images/001.jpg images/002.jpg images/000.jpg

space:= $(empty) $(empty)
newline:= '\n'
listtxt:= $(subst $(space),$(newline),$(images)) 
# subst is a way to do string replacements, it works like this: $(subst $(delimitator),$(replacement),$(list))
# it's used here to make a list of the images, with one filename on each line

tesseract:
	echo $(listtxt) > src/list.txt
	tesseract src/list.txt src/plain

myscript: tesseract
	cat src/plain.txt | python3 src/myscript.py > output/a-new-file.txt

myscript.py

from sys import stdin, stdout

txt = stdin.read()
output = txt.replace(' the ', ' ******a***** ')
stdout.write(output)