subst

#!/bin/sh
# Substitute a string in many files. By Serge van den Boom, 20020826

# We need bash functionality. Executing bash with the shebang won't be
# portable as the location of bash differs.
if [ -z "$BASH_VERSION" ]; then
	exec bash "$0" "$@"
fi

if [ $# -eq 0 ]; then
	{
		echo "subst: substitute a string in a lot of files."
		echo "By Serge van den Boom, 20020826"
		echo "Usage: subst <pattern> <file> [...]"
		echo -n "'pattern' should be a pattern in the form used by sed, "
		echo " like 's/old/new/g'."
	} 1>&2
	exit 1
fi

PAT="$1"
SEP="${PAT:1:1}"
GREPPAT="${PAT:2}"
eval GREPPAT='${GREPPAT%%'$SEP'*}'
shift
while [ "$#" -gt "0" ]; do
	FILE="$1"
	echo -n "$FILE: "
	grep -q "$GREPPAT" < "$FILE"
	EXITVAL=$?
	case $EXITVAL in
		0)  # Match found
			;;
		1)  # No match found
			echo "Nothing to do."
			shift
			continue
			;;
		*)
			echo "ERROR"
			echo "Error: grep returned exit value ${EXITVAL}. Aborted." 1>&2
			exit 1
	esac
	TEMPFILE="${FILE}.patchtree.$$.tmp"
	mv -- "$FILE" "$TEMPFILE"
	sed -e "$PAT" < "$TEMPFILE" > "$FILE"
	rm -- "$TEMPFILE"
	echo "Done."
	shift
done