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File access time does not change on some files


 
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# 1  
Old 03-16-2011
File access time does not change on some files

Hey All,
I want to get the access time of files in a directory.

I used ls -lu on a directory and picked a file that had the access time of Mar 1 and used cat to get the contents of the file. Then I used the ls -lu again and the access time changed on that file. Perfect !!

Now if I cat a file that has an access time of 3/16 say 2 pm and then check the ls -lu output, the access time does not change.

So, the access time changes on some files and not on the others.

Just to clarify, these files are stored on my local computer.

Any help will be appreciated.

Thanks,
V.
# 2  
Old 03-16-2011
Are these files on different partitions, by any chance? It's possible to turn atime's off for certain partitions to increase performance. (i.e. avoid a potential disk write every darn time you read a file Smilie )

This of course depends on your system, which we haven't the faintest idea what it is yet. What is it?
# 3  
Old 03-16-2011
Thanks for the reply. The files are on the same partition. I am using Ubuntu 10.10. The files are in subdirectories under my home directory.
# 4  
Old 03-16-2011
Hm, how odd. Could you copy-paste an example?
# 5  
Old 03-17-2011
For example:
Code:
root@gupta:/home/gupta/Desktop/my_stuff/test# ls -lu xls.php 
-rw-r--r-- 1 gupta gupta 3947 2011-03-01 10:46 xls.php

root@gupta:/home/gupta/Desktop/my_stuff/test# cat xls.php

--- contents of the file ---

root@gupta:/home/gupta/Desktop/my_stuff/test# ls -lu xls.php 
-rw-r--r-- 1 gupta gupta 3947 2011-03-17 08:53 xls.php

so in the above example, the access time changes when we cat the file.

Now look at the following example -
Code:
root@gupta:/home/gupta/Desktop/my_stuff/tmp# ls -lu idxx.txt 
-rw-r--r-- 1 gupta gupta 1189 2011-03-16 14:35 idxx.txt

root@gupta:/home/gupta/Desktop/my_stuff/tmp# cat idxx.txt

--- contents of the file ----

root@gupta:/home/gupta/Desktop/my_stuff/tmp# ls -lu idxx.txt 
-rw-r--r-- 1 gupta gupta 1189 2011-03-16 14:35 idxx.txt

In this example, the access time does not change.

Thanks for any input.
V.

Moderator's Comments:
Mod Comment Please use [code] and [/code] tags when posting code, data or logs etc. to preserve formatting and enhance readability, thanks.

Last edited by zaxxon; 03-17-2011 at 10:30 AM.. Reason: code tags
# 6  
Old 03-17-2011
Please run "df -k xls.php" and "df -k idxx.txt" and post the results. These commands reveal which file systems contain the files. I will be surprised if both files reside in the same file system.
# 7  
Old 03-17-2011
Thanks Perderabo, here is the output of df -k:
Code:
root@gupta:/home/gupta/Desktop/my_stuff/tmp# df -k idxx.txt 
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1            937339832  42780124 846945552   5% /

root@gupta:/home/gupta/Desktop/my_stuff/test# df -k xls.php 
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1            937339832  42780124 846945552   5% /

 

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