Hi all!
I am relatively new to UNIX staff, and I have come across a problem:
I have a big directory, which contains 100 smaller ones. Each of the 100 contains a file ending in .txt , so there are 100 files ending in .txt
I want to split each of the 100 files in smaller ones, which will contain... (4 Replies)
$mystring = "name:blk:house::";
print "$mystring\n";
@s_format = split(/:/, $mystring);
for ($i=0; $i <= $#s_format; $i++) {
print "index is $i,field is $s_format";
print "\n";
}
$size = $#s_format + 1;
print "total size of array is $size\n";
i am expecting my size to be 5, why is it... (5 Replies)
I have gone through all the threads in the forum and tested out different things. I am trying to split a 3GB file into multiple files. Some files are even larger than this.
For example:
split -l 3000000 filename.txt
This is very slow and it splits the file with 3 million records in each... (10 Replies)
Hi,
I have some output in the form of:
#output:
abc123
def567
hij890
ghi324
the above is in one column, stored in the variable x ( and if you wana know about x... x=sprintf(tolower(substr(someArray,1,1)substr(userArray,3,1)substr(userArray,2,1)))
when i simply print x (print x) I get... (7 Replies)
Hi... I have a question regarding the split function in PERL.
I have a very huge csv file (more than 80 million records). I need to extract a particular position(eg : 50th position) of each line from the csv file. I tried using split function. But I realized split takes a very long time.
Also... (1 Reply)
Hi... I have a question regarding the split function in PERL.
I have a very huge csv file (more than 80 million records). I need to extract a particular position(eg : 50th position) of each line from the csv file. I tried using split function. But I realized split takes a very long time.
Also... (0 Replies)
Hi... I have a question regarding the split function in PERL.
I have a very huge csv file (more than 80 million records). I need to extract a particular position(eg : 50th position) of each line from the csv file. I tried using split function. But I realized split takes a very long time.
Also... (1 Reply)
my @d =split('\|', $_);
west|ACH|3|Y|LuV|N||N||
Qt|UWST|57|Y|LSV|Y|Bng|N|KT|
It Returns d as 8 for First Line, and 9 as for Second Line . I want to Process Both the Files, How to Handle It. (3 Replies)
Hello;
I have a file consists of 4 columns separated by tab. The problem is the third fields. Some of the them are very long but can be split by the vertical bar "|". Also some of them do not contain the string "UniProt", but I could ignore it at this moment, and sort the file afterwards. Here is... (5 Replies)
Discussion started by: yifangt
5 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)