What is the match group syntax in Eclipse's search and replace

Use $1 instead of \1

For the /g global replace flag, use the Replace All button:

_{(source: bpsite.net)}

Note: The above is the Find/Replace dialog for a single file, comes up for Ctrl-F

For working across multiple files, default shortcut is Ctrl-H, and the dialogs are a bit different:

In the Find Field: log(.*)

Int the Replace With Field: log$1 debug