Take the tour ×  On Ubuntu 12.04 I did the following    1. stat
a file   2. cat the same file   3. stat the file again   4. cat
the file again after 5 min   5. stat the file  The access time
reported at 3. reflects the point at which 2. was run. However,
the access time reported at 5. coincides with 2. and not 4. Is
this because Linux serves the file out of cache and avoids disk
access in the second instance? Also is there a way to retrieve a
list of files that are currently resident in disk cache?
share|improve this question add comment  2 Answers  up vote 3
down vote accepted  Caching is transparent. It does not affect a
file's metadata. A file's access date shows when the file was
read, never mind whether reading the file caused a read from the
disk.  By default, Linux does not update file access times. The
default mount option sine kernel 2.6.30 is relatime, which
sacrifices the usefulness of file access times for a small
performance gain. It seems that your filesystem is mounted with
the relatime option