How to Find & Replace a String Within Files with Find / Grep / Sed

find *.ini -type -f > stack

while read line 
do
sed -i s"@Source =@Source = C:\software\dx4@" "${line}"
done < stack

Assuming that a} You have sed with "-i" (the insert flag, which AFAIK is not always portable) and b} sed doesn't crap itself about a double escape sequence, I think that will work.

With GNU awk for the 3rd arg to match(), gensub(), and "inplace" editing:

awk -i inplace '
    match($0,/(.*Source = C:\software\){filename}(.*)/,a) {
        fname = gensub(/..*/,"",1,FILENAME)
        $0 = a[1] fname a[2]
    }
1' *.INI

The above assumes you're running in a UNIX environment though your use of the term folder instead of directory and that path starting with C: and containing backslashes makes me suspicious. If you're on Windows then save the part between the 2 's (exclusive) in a file named foo.awk and execute it as awk -i inplace foo.awk *.INI or however it is you normally execute commands like this in Windows.

If you want to edit a file in a script, I think ed is the way to go. Combined with a shell for loop:

for file in *.INI; do
    base=$(basename "$file" .INI)
    ed -s "$file" <<EOF
/^Source =/s/=/= C:\\software\\$base/
w
EOF
done

(This does assume that filenames will not have newlines or ampersands in their names)

You can try with sed For example

Input file contents: file.txt

Source =
some lines..

script:

newstring='Source = C:softwaredx4'
oldstring='Source ='
echo `sed "s/$oldstring/$newstring/g" file.txt` > file.txt

After running the above commands output:

Source = C:softwaredx4
some lines..