replace_tabs

#!/bin/sh

# replace tabs with spaces in files in given as argument
#
# wraps expand so that students are unlikely to lose data
# assumes tabs are 4 spaces
#
# Repo: https://github.com/COMP1511UNSW/c_check

TAB_SIZE=4
PATH=/bin:/usr/bin:$PATH

for file in "$@"
do
	backup_file="$file.original_with_tabs"

	if test -e "$backup_file"
	then
		echo "$0: can not backup '$file' to '$backup_file' because it already exists" 1>&2
		echo "rename or remove '$backup_file' and rerun" 1>&2
		exit 1
	fi

	mv "$file" "$backup_file" || exit 1

	if expand -it 4 "$backup_file" >"$file"
	then
		if diff  "$backup_file" "$file" >/dev/null
		then
			mv "$backup_file" "$file"
			echo "$0: no tabs found in $file"
		else
			echo "mv $file $backup_file"
			echo "expand -it $TAB_SIZE $backup_file >$file"
			chmod --reference="$backup_file" "$file"
			echo "$0: tabs replaced in '$file', original contents left in '$backup_file'"
		fi
	else
		mv "$backup_file" "$file"
		echo "$0: tab expansion failed" 1>&2
		exit 1
	fi
done

exit 0