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From: jon@jonlab.UUCP (Jon H. LaBadie)
Newsgroups: comp.unix.admin
Subject: Re: What action updates a file's ACCESS time?
Summary: access is transfer of file data to memory, generally kernel buffers
Keywords: file access time
Message-ID: <893@jonlab.UUCP>
Date: 4 Dec 90 15:02:40 GMT
References: <331@twg.bc.ca> <1990Nov23.102257.10747@cnix.uucp>
Organization: 4455 Province Line Rd., Princeton, NJ 08540
Lines: 22

In article <331@twg.bc.ca> bill@twg.bc.ca (Bill Irwin) writes:
>I would like to know ALL the possible activities that could result in a file's
>access  time (ls -lu) being updated.

The way to look at this is that any activity that requires looking at
the data in the file (not the inode contents) will update the access
time.  Copies will, moves on the same file system shouldn't.  File type
checks probably will.  Grep's definitely will.

Note also that write's to a file require a read first.  You may want to
write one character.  But disks transfer data in blocks.  Thus, to
write your one character, the block it will be written in must be read
into memory.  You will "write" your one character into that memory
buffer and the entire block will be written to disk.

Thus writes also update access times.

Jon

-- 
Jon LaBadie
{att, princeton, bcr, attmail!auxnj}!jonlab!jon