how to know list of files accessed

how to know list of files accessed

[ranjith kumar]

Hi,
Suppose I downloaded linux kernel.
When I run "make", many of the .c files will be compiled.
I want to know which .c files are compiles and which .c files are not compiled.
Is there any way to know in linux?

Access time of the files which are compiled is not getting modified
when I run "make" . why?

Thanks in advance.

Re: how to know list of files accessed

[Michael Opdenacker]

Hi Ranjith,

On 02/13/2012 12:30 PM, ranjith kumar wrote:
> Hi,
> Suppose I downloaded linux kernel.
> When I run "make", many of the .c files will be compiled.
> I want to know which .c files are compiles and which .c files are not compiled.
> Is there any way to know in linux?
An easy way is to run your command with 'strace' to trap all the calls
to 'open':

strace make 2>&1 | grep open
>
> Access time of the files which are compiled is not getting modified
> when I run "make" . why?
That's correct. As long as you don't read these files, there's no reason
to update their latest access time. Comparing access time with modified
time is a useful way to know which files haven't been read after being
modified.

Cheers

Michael.
-- 
Michael Opdenacker, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
+33 484 253 396

Re: how to know list of files accessed

[Valdis.Kletnieks]

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On Mon, 13 Feb 2012 13:32:56 +0100, Michael Opdenacker said:

> An easy way is to run your command with 'strace' to trap all the calls
> to 'open':
>
> strace make 2>&1 | grep open

You really want 'strace -f make' - the -f flag makes it follow forks, which you
want to do because it's gcc that's doing most of the actual file I/O, not make.

Oh.  and you want to redirect that grep into a temporary file and be
prepared to post-process it with perl or something, there's going to be
*zillions* of open() syscalls.

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Re: how to know list of files accessed

[Matthias Schniedermeyer]

On 13.02.2012 23:44, Valdis.Kletnieks@vt.edu wrote:
> On Mon, 13 Feb 2012 13:32:56 +0100, Michael Opdenacker said:
> 
> > An easy way is to run your command with 'strace' to trap all the calls
> > to 'open':
> >
> > strace make 2>&1 | grep open
> 
> You really want 'strace -f make' - the -f flag makes it follow forks, which you
> want to do because it's gcc that's doing most of the actual file I/O, not make.
> 
> Oh.  and you want to redirect that grep into a temporary file and be
> prepared to post-process it with perl or something, there's going to be
> *zillions* of open() syscalls.

Inotify is certainly easier.

When inotifywait from inotify-tools is available:
inotifywait -m -r -e open <dir> > files.opened

This monitors recusivly for the "open" event and writes it into 
files.opened.

In my case that is:
wc -l files.opened
1115553 files.opened

And this number of unique files with directories
sort < files.opened | uniq | wc -l
5454

And this number af unique fiels without dirs.
cat files.opened | grep -v ISDIR | sort | uniq | wc -l
3837

I use "O=../compile_dir" to get the output into another dir, if you 
don't do that all newly created files are also counted, as you also 
"open" them.




Bis denn

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