AstroGrep is not available for Linux but there are some alternatives that runs on Linux with similar functionality. The best Linux alternative is DocFetcher, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to AstroGrep and nine of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to AstroGrep are grep (Free, Open Source), Search Monkey (Free, Open Source), The Silver Searcher (Free, Open Source) and regexxer (Free, Open Source).
DocFetcher is a portable German/English open source desktop search application. It allows you search the contents of documents on your computer. - You can think of it as Google for your local document repository.
regexxer is a nifty GUI search/replace tool featuring Perl-style regular expressions. If you need project-wide substitution and you’re tired of hacking sed command lines together, then you should definitely give it a try.
Rummage is a cross platform tool for crawling directories and searching and replacing in text files. It is written in Python and uses wxPython for the GUI. Rummage allows for literal or regex searches and has configurations for limiting the files etc.
KFileReplace is a KDE utility that replace some strings with others in a lot of files in an only operation. Then it's very easy to update some URLs, filenames, ... which are written in all files of a project.