Recursively remove all the files that don't have the specified extension.

cleanup_workspace.sh

find . -type f ! -name "*.c" ! -name "*.h" ! -name "*.json" ! -name "*.py" ! -name "*.sh" ! -name "*.md" -exec rm {} \;

# This (recursively) removes any files that don't end with the above extensions

compile_directory.sh

# code to compile one whole project (directory)
# Won't work if 
#   you have multiple folders
#   you execute this from outside the project directory
COMPILER_INPUT="$(find ./$1 -type f -name "*.c")";
gcc $COMPILER_INPUT -o "./$1/a.out";

Makefile

# Better than the rest, a frickin' makefile!
# https://www.cs.colby.edu/maxwell/courses/tutorials/maketutor/
CC=gcc
CFLAGS=-I.
DEPS = header_file.h
OBJ = file1.c file2.c and_so_on.c

%.o: %.c $(DEPS)	# for compiling the object code
	$(CC) -c -o $@ $< $(CFLAGS)

main: $(OBJ)	# for the final main file
	$(CC) -o $@ $^ $(CFLAGS)