I wonder if there is a program (e.g. in the shell) for collecting statistics regarding how often files are written to? Basically I would like to compile a list of the files most often modified on my computer during some period of time. I know one could in some way "manually" use the mtime of the files, but I'd prefer an already existing solution if such exists.

I'm intending to set up a Linux system run entirely from a USB flash memory and I would like to know which part of the file system to put on a jffs2 partition, i.e. the most frequently modified files, hence my question above.

Thank you.

If you would like a fine-grained view of that you would (AFAIK) have to intercept syscalls like write. Else maybe use some form of SAR or lsof (select by fd, write access). Guesstimating and depending on usage I'd say ordered top four: /var (logs), /tempdirs (obvious), /home and /etc (sporadically).

Thank you for your reply unSpawn. Unfortunately I cannot see exactly how to use these tool in order to accomplish what I intended in a straight forward way (tried atsar and lsof).

Thanks for your "guesstimations" regarding disk usage.

Atsar would be kind of coarse since it only measures writes per partition so you would have to have a per root dir partition setup. Not impossible but also not the easiest thing to wedge in later on ;-p Lsof only produces one time results so you would have to run a periodical script that parses lsof output, checks which files are open for writing and check process age wrt longevity. The script itself isn't that hard to produce, but I wonder if Real Life fine-grained results would matter wrt the guesstimate. If due to usage you can for instance predict a lot of short-lived temp-writing processes, putting tempdirs on a small tmpfs could be beneficial wrt speed and wear n tear.

A lot of embeded systems don't have a /var for this reason.
Depends on what you want to do.. it has its pros and cons.
Or they are in ram.