Hi, on my previous posting I have another questing: I create my compression stream with bio::filtering_streambuf< bio::input > l_deflate; switch (m_compress) { case gzip : l_deflate.push( bio::gzip_compressor() ); break; case bzip2 : l_deflate.push( bio::bzip2_compressor() ); break; } For a single file I push it to zip with: l_deflate.push( bio::file_source(p_str1, BOOST_IOS::binary) ); I need a concatination for two files like: l_deflate.push( bio::file_source(p_str1, BOOST_IOS::binary) ); l_deflate.push( bio::file_source(p_str2, BOOST_IOS::binary) ); for unix shell I do this with: cat file1.txt > tozip.txt cat file2.txt >> tozip.txt How I can push a concatinated file to the deflate stream buffer? Thanks Phil