Handle another fiddly special case in HTML back-link generation.

[sgt/agedu] / agedu.but

diff --git a/agedu.but b/agedu.but
index 5bf5d0b..f4fdb1d 100644 (file)
--- a/agedu.but
+++ b/agedu.but
@@ -443,6 +443,20 @@ complexity.)
 
 }
 
 
 }
 

+\dt \cw{--mtime}
+
+\dd This option causes \cw{agedu} to index files by their last
+modification time instead of their last access time. You might want
+to use this if your last access times were completely useless for
+some reason: for example, if you had recently searched every file on
+your system, the system would have lost all the information about
+what files you hadn't recently accessed before then. Using this
+option is liable to be less effective at finding genuinely wasted
+space than the normal mode (that is, it will be more likely to flag
+things as disused when they're not, so you will have more candidates
+to go through by hand looking for data you don't need), but may be
+better than nothing if your last-access times are unhelpful.
+

 The following options affect the web server mode \cw{-w}, and in one
 case also the stand-along HTML generation mode \cw{-H}:
 
 The following options affect the web server mode \cw{-w}, and in one
 case also the stand-along HTML generation mode \cw{-H}:
 


@@ -558,11 +572,13 @@ efficiently perform the queries it needs; this data structure
 requires \cw{O(N log N)} storage. This is larger than you might
 expect; a scan of my own home directory, containing half a million
 files and directories and about 20Gb of data, produced an index file
 requires \cw{O(N log N)} storage. This is larger than you might
 expect; a scan of my own home directory, containing half a million
 files and directories and about 20Gb of data, produced an index file

-nearly a third of a Gb in size. Furthermore, since the data file
-must be memory-mapped during most processing, it can never grow
-larger than available address space, which means that any use of
-\cw{agedu} on a file system more than about ten times the above size
-is probably going to have to be done on a 64-bit computer.
+over 60Mb in size. Furthermore, since the data file must be
+memory-mapped during most processing, it can never grow larger than
+available address space, so a \em{really} big filesystem may need to
+be indexed on a 64-bit computer. (This is one reason for the
+existence of the \cw{-D} and \cw{-L} options: you can do the
+scanning on the machine with access to the filesystem, and the
+indexing on a machine big enough to handle it.)

 
 The data structure also does not usefully permit access control
 within the data file, so it would be difficult \dash even given the
 
 The data structure also does not usefully permit access control
 within the data file, so it would be difficult \dash even given the