bwBASIC/rmvspcs

#!/bin/bash
# 4-2020 Ken
echo "Input file to clean leading spaces "
read infile
if [ -r $infile ]
then
	echo "Wait, copying original input file to $infile.cpy"
	cp $infile $infile.cpy
else
	echo "Input file is unreadable"
	exit 1
fi
# Sucessively delete leading spaces
ed $infile <<!
1,\$ s/^ //
1,\$ s/^ //
1,\$ s/^ //
1,\$ s/^ //
w $infile
\$=
q
!
exit 0