If you don't know what you want, I have no idea whether what I suggest will succeed. I am guessing that the intent of the pipeline:
is to extract the first 10000*1000 bytes from /var/dump.log and then extract the first 6000*1000 bytes from that. That is equivalent to extracting the first 6000*1000 bytes from /var/dump.log. If you had specified 10000kB and 6000kB, that is what would be done according to the Linux head man page. If you had used 10000K and 6000K, the multiplier would be 1024 instead of 1000 according to the Linux head man page. If the count had been negative in the 2nd call to head, the command line would make more sense since it would then be getting the last 6000*(1000 or 1024) bytes from the first 10000*(1000 or 1024) bytes. But, I can only work with the command line you supplied and guess at the multiplier (or block size) you want. So:
might do what you want. If you want a block size of 1024 instead of 1000, change the bs=1000 to bs=1024.
If wanted the last 6000 blocks of the first 10000 blocks from the file, you could try:
This User Gave Thanks to Don Cragun For This Post:
:mad: I did this the other day but one of my support personnel removed my history so i could call it back up to remeber the exact command since i am air-headed at times. I am trying to take a 30 MEG file off the system and drop it to tape then i want to make the file go back to being 0 bytes so... (1 Reply)
I'm doing a bit of hex editing with dd and I can replace values fairly simply. However, I've run across a situation where I need to delete bytes in the file and I'm not sure how to do that. For example:
Input file has:
1234567890
Output needs to be:
123abc90
I tried this:
printf... (6 Replies)
Hi all,
Does anybody know or guide me on how to remove the first N bytes and the last N bytes from a binary file? Is there any AWK or SED or any command that I can use to achieve this?
Your help is greatly appreciated!!
Best Regards,
Naveen. (1 Reply)
What is the easiest way to inspect the bytes stored in a file?
Ideally, If my file was 10 bytes each of which had only the high bit set, I'd be able to browse for it and get output like this:
01 - 10000000
02 - 10000000
03 - 10000000
04 - 10000000
05 - 10000000
06 - 10000000
07 -... (7 Replies)
Hi Guyz,
I need to capture first N Bytes from the first line of my file.
Eg. If i have following data in File1
414d51204541495052475731202020204a910846230e420c Hello 3621363663212 Help Required
Then, i want the value of first 48 Bytes to be stored in a variable.
That is, variable... (5 Replies)
While running script I am getting an error like
Few lines in data are not being processed.
After googling it I came to know that adding such line would give some memory to it
ini_set("memory_limit","64M");
my input file size is 1 GB.
Is that memory limit is based on RAM we have on... (1 Reply)
Hi,
If I want to copy a 1024 byte data stream in to the target location in 3-bytes chunk, I guess I can use the following script.
dd bs=1024 count=3 if=/src of=/dest
But, I would like to know, how to do it via a C program. I have tried this with memcpy(), that did not help. (3 Replies)
Hello guys. I really hope someone will help me with this one..
So, I have to write this script who:
- creates a file home/student/vmdisk of 10 mb
- formats that file to ext3
- mounts that partition to /mnt/partition
- creates a file /mnt/partition/data. In this file, there will... (1 Reply)
hello,
suppose, entered input is of 1-40 bytes, i need it to be converted to 40 bytes exactly.
example: if i have entered my name anywhere between 1-40 i want it to be stored with 40 bytes exactly.
enter your name:
donald duck (this is of 11 bytes)
expected is as below - display 11... (3 Replies)
Discussion started by: shravan.300
3 Replies
LEARN ABOUT DEBIAN
bup-margin
bup-margin(1) General Commands Manual bup-margin(1)NAME
bup-margin - figure out your deduplication safety margin
SYNOPSIS
bup margin [options...]
DESCRIPTION
bup margin iterates through all objects in your bup repository, calculating the largest number of prefix bits shared between any two
entries. This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids.
For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45. That means a 46-bit
hash would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by
its first 46 bits.
The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects. Since SHA-1 hashes have 160 bits,
that leaves 115 bits of margin. Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits
with far fewer objects.
If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see if
you're getting dangerously close to 160 bits.
OPTIONS --predict
Guess the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer
from the guess. This is potentially useful for tuning an interpolation search algorithm.
--ignore-midx
don't use .midx files, use only .idx files. This is only really useful when used with --predict.
EXAMPLE
$ bup margin
Reading indexes: 100.00% (1612581/1612581), done.
40
40 matching prefix bits
1.94 bits per doubling
120 bits (61.86 doublings) remaining
4.19338e+18 times larger is possible
Everyone on earth could have 625878182 data sets
like yours, all in one repository, and we would
expect 1 object collision.
$ bup margin --predict
PackIdxList: using 1 index.
Reading indexes: 100.00% (1612581/1612581), done.
915 of 1612581 (0.057%)
SEE ALSO bup-midx(1), bup-save(1)BUP
Part of the bup(1) suite.
AUTHORS
Avery Pennarun <apenwarr@gmail.com>.
Bup unknown-bup-margin(1)