9 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
How does unix system administration, unix programming, unix network programming differ?
Please help. (0 Replies)
Discussion started by: thulasidharan2k
0 Replies
2. Programming
hey guys.
im currently trying to make a program in unix (redhat, compiling the .c file using gcc) and i need urgent urgent help.
i need to save objects of structures in a file but they dont seem to be saving properly. ive been on it for a whole day now. dunno why i cant do it.
when i try to... (4 Replies)
Discussion started by: mjumrani
4 Replies
3. UNIX for Dummies Questions & Answers
I asked this over on the "High Level Programming Section" but there must be a secret handshake or something that I am missing.....anyway....if a person wanted to start some C programming in UNIX what would be the best compiler to start with ??
I am fairly familiar with visual studio and have done... (2 Replies)
Discussion started by: zapper222
2 Replies
4. UNIX for Dummies Questions & Answers
Hello,
I am trying to learn Networking Programming in C in unix enviorment. I want to know how good it is to become a network programmer. i am crazy about Network programming but i also want to opt for the best carreer options. Anybody experienced Network Programmer, please tell me is my... (5 Replies)
Discussion started by: vibhory2j
5 Replies
5. Shell Programming and Scripting
Several months ago I found a link that explained the difference between how a Unix Systems Admin would do scripting compared to what a Unix Programmer would do.
It showed a basic script and then show several iterations that explained how the Systems Admin would change it to make it better. I was... (0 Replies)
Discussion started by: BCarlson
0 Replies
6. UNIX for Dummies Questions & Answers
hi guys,
I m from india. I m working as programmer in one of MNC. Since 3 years im working on Microsoft platform on dot net and platforms.
but now i decided to shift my future to unix , Linux side. I want to be the part of this open source family.
and with this i want to make my future also.... (6 Replies)
Discussion started by: d_swapneel14
6 Replies
7. UNIX for Advanced & Expert Users
hi guys,
I m from india. I m working as programmer in one of MNC. Since 3 years im working on Microsoft platform on dot net and platforms.
but now i decided to shift my future to unix , Linux side. I want to be the part of this open source family.
and with this i want to make my future also.... (3 Replies)
Discussion started by: d_swapneel14
3 Replies
8. Programming
i would like advice on the usbject of c programming (in the middle of reading a book on C). could i benefit more if i apply that knowledge in the unix format if i were able to, or would that take the point out of learning C, basically I want to stay away from strying too far away from unix and use... (1 Reply)
Discussion started by: moxxx68
1 Replies
9. UNIX for Dummies Questions & Answers
can someone tell me some programming commands on unix? (2 Replies)
Discussion started by: fretis
2 Replies
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)
