($a,$f,$t,$k)=@ARGV;print"Content-Type: text/",!$a?plain:"tab-separated-values
Content-Disposition: attachment;filename=log.csv","\n\n";$k=~s/%([\da-f]{2})/
pack"H2",$1/egi;$f?do{/^\d{8}$/&&(open(F,"$_.txt"),print grep$k?/\Q$k/o:1,<F>)
for$f..$t||$f}:do{s/^\d$/0$&/for($s,$n,$h,$d,$m,$y)=localtime;$y+=1900;$m++;$m
=~s/^\d$/0$&/;open F,">>$y$m$d.txt";print F join("\t",$h,$n,$s,
@ENV{REQUEST_URI,REMOTE_ADDR,HTTP_USER_AGENT,HTTP_REFERER}),"\n"}

・検索ワードを URI-unescape
・第 3 引数を省略可能に
・パラメータをクエリ渡しから引数渡しへ
　　(例)
　　http://hoge.com/7accesslog.cgi?1+20040301+20040331+MSIE%205
　　http://hoge.com/7accesslog.cgi?1+20040301