Sed and grep regex syntaxes differ - regex

Question

This is a part of my shell script, which I use to perform a recursive find and replace in the working directory. Backup and other utilities are in other functions, which are irrelevant to my problem.
#!/bin/bash
# backup function goes here
# #param $1 The find pattern.
# #param $2 The replace pattern.
function findAndReplace {
bufferFile=/tmp/tmp.$$
filesToReplace=`find . -type f | grep -vi cvs | grep -v '#'`
sedPattern="s/$1/$2/g"
echo "Using pattern $sedPattern"
for f in $filesToReplace; do
echo "sedding file $f"
sed "$sedPattern" "$f" > "$bufferFile"
exitCode=$?
if [ $exitCode -ne 0 ] ; then
echo "sed $sedPattern exited with $exitCode"
exit 1
fi
chown --reference=$f $bufferFile
mv $bufferFile $f
done
}
backup
findAndReplace "$1" "$2"
Here's a sample usage: recursive-replace.sh "function _report" "function report".
It works, but there is one problem. It uses sed on ALL files in the working directory. I would like to sed only those files, which contain the find pattern.
Then, I modified the line:
filesToReplace=`find . -type f | grep -vi cvs | grep -v '#'`
to:
filesToReplace=`grep -rl "$1" . | grep -vi cvs | grep -v '#'`
And it works too, but not for all find patterns. E.g. for pattern \$this->report\((.*)\) I recieve error: grep: Unmatched ( or \(. This pattern is correct for sed, but not for grep.
Regex syntaxes for grep and sed differ. What can I do?

Answer 1

use grep -E ("extended" regexp option) — it usually solves the problem.
(also sometimes available as egrep)
Also, why not keep using find?
filesToReplace=`find . -name CVS -prune -o -type f -exec grep -l "$1" {} \; | grep -v '#'`
Also note the -i option of sed, which allows in-place changes in files and the removal of the bufferFile/chown/mv logic.

Answer 2

Why not compare source and buffer files before overwriting the source file:
#!/bin/bash
# backup function goes here
# #param $1 The find pattern.
# #param $2 The replace pattern.
function findAndReplace {
bufferFile=/tmp/tmp.$$
filesToReplace=`find . -type f | grep -vi cvs | grep -v '#'`
sedPattern="s/$1/$2/g"
echo "Using pattern $sedPattern"
for f in $filesToReplace; do
echo "sedding file $f"
sed "$sedPattern" "$f" > "$bufferFile"
exitCode=$?
if [ $exitCode -ne 0 ] ; then
echo "sed $sedPattern exited with $exitCode"
exit 1
fi
cmp -s $f $bufferFile
if [ $? -ne 0 ]; then
chown --reference=$f $bufferFile
mv $bufferFile $f
fi
done
}
backup
findAndReplace "$1" "$2"