X-Git-Url: https://www.fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=finddup.1;h=faaef4de3dc324f2786f6ebb38cf48608c5a926f;hb=d2131aa73229a6e713cca1ca95b714ff8e68ca12;hp=9cc21b4f13e9f2c5536f0a89423ab9c37bc0a240;hpb=a61c9478f31b957e0d4007df9feddd6f0139ccf8;p=finddup.git

diff --git a/finddup.1 b/finddup.1
index 9cc21b4..faaef4d 100644
--- a/finddup.1
+++ b/finddup.1
@@ -63,16 +63,28 @@ show the real path of the files
 files with same inode are considered as different
 .TP
 \fB-m\fR, \fB--md5\fR
-use MD5 hashing
+use MD5 hashing (if compiled with the option)
 
 .SH "BUGS"
 
 None known, probably many. Valgrind does not complain though.
 
-The MD5 hashing often hurts more than it helps, hence it is off by
-default. The only case when it should really be useful is when you
-have plenty of different files of same size, which does not happen
-often.
+The MD5 hashing is not satisfactory. It is computed for a file only if
+the said file has to be read fully for a comparison (i.e. two files
+match and we have to read them completely).
+
+Hence, in practice lot of partial MD5s are computed, which costs a lot
+of cpu and is useless. This often hurts more than it helps. The only
+case when it should really be useful is when you have plenty of
+different files of same size, and lot of similar ones, which does not
+happen often.
+
+Forcing the files to be read fully so that the MD5s are properly
+computed is not okay neither, since it would fully read certain files,
+even if we will never need their MD5s.
+
+Anyway, it has to be compiled in with 'make WITH_MD5=yes', and even in
+that case it will be off by default
 
 .SH "WISH LIST"