see inline
From: Raz <raziebe@xxxxxxxxx>
To: Karl Tatgenhorst <karl.tatgenhorst@xxxxxxxxx>
Cc: Manish Katiyar <mkatiyar@xxxxxxxxx>; kernelnewbies <kernelnewbies@xxxxxxxxxxxx>
Sent: Thursday, 23 October, 2008 1:14:18 AM
Subject: Re: any one knows how to truncate a file from its begining ?
I think XFS can do it . it has some un/reserve space ioctl.
3521 /*
3522 * XFS_IOC_RESVSP and XFS_IOC_UNRESVSP will reserve or unreserve
3523 * file space.
3524 * These calls do NOT zero the data space allocated to the file,
3525 * nor do they change the file size.
3526 *
3527 * XFS_IOC_ALLOCSP and XFS_IOC_FREESP will allocate and free file
3528 * space.
3529 * These calls cause the new file data to be zeroed and the file
3530 * size to be changed.
3531 */
<kanishk>
unreserve/reserve do not allocate/deallocate the blocks to the file where as the rest 2 do ....
+
These do not affect the file size.......
thankx
kanishk
On Wed, Oct 22, 2008 at 8:07 PM, Karl Tatgenhorst
<karl.tatgenhorst@xxxxxxxxx> wrote:
> if it is a binary file, use dd and figure out the offset to start from
> (man dd will help). If it is a text file just use some perl like this:
>
>
>
> #open your file here
>
> $count=0;
> $start_removing= 100; ###starting at 100
> $stop_removing= 300; ###end of block to remove
> while<FILE> {
> $count++;
> if(100 < $count < 300) {
> next;
> }
> print $_
> }
>
> both methods create a copy of the file and you can just copy your file over it.
>
> good luck
>
>
> On Wed, Oct 22, 2008 at 12:31 PM, Raz <raziebe@xxxxxxxxx> wrote:
>> no.
>> I mean i want to remove a portion of the file :
>> if a file is composed of : a,b,c,d blocks.
>> I want to be able to remove from the **disk** block c or block a.
>> ftruncate remove the end.
>>
>> On Wed, Oct 22, 2008 at 7:24 PM, Manish Katiyar <mkatiyar@xxxxxxxxx> wrote:
>>> On Wed, Oct 22, 2008 at 10:42 PM, Raz <raziebe@xxxxxxxxx> wrote:
>>>> or a file system that can do it ?
>>>
>>> What does that mean ???
>>>
>>> just doing
>>>
>>> $ > filename
>>> on command line will truncate it............or probably "man
>>> ftruncate" can help you.
>>>
>>> Thanks -
>>> Manish
>>>
>>>
>>>>
>>>> thank you
>>>> raz
>>>>
>>>> --
>>>> To unsubscribe from this list: send an email with
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>>>> Please read the FAQ at http://kernelnewbies.org/FAQ
>>>>
>>>>
>>>
>>
>> --
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>>
>>
>
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