Then I realized this is probably the most useless command that you can imagine. Yes, perhaps it could assert that there is still a working filesystem, but I am not sure about it.
What do you think?
Can you think of any more useless commands?
Hi mates,
A newbe in UNIX world. how can i add a specific path to my default unix path. ie i want to add a directory let is say /abdul to the path and whenever i log in unix should recognize it. it is mostly importnant when i use the cc command to compile my c programs ...and i have to use ./cc... (2 Replies)
Hi, I came across with this line "set -x" in the beginning of a script, but i can't find one logic reason for this... should be something else after, i think.... anyone can help?
tanx (2 Replies)
Hi All,
I am trying to install the IBM data set generator. I have to use the Solaris to use this tool. The following link is supposed to tell the steps on how to use the IBM tool on the Solaris server.
IBM Quest Market-Basket Synthetic Data Generator
Unfortunately, I don't understand what is... (2 Replies)
Hello;
I work now with a team which has based her "applications" on the following schema:
1 NFS client C1 (linux redhat 5) writes a file fic.dat on a NFS SERVER S (RH 5)
Another NFS client C2 is waiting for the same file fic.dat (on NFS server S1), and, when "fic.dat" appears, then makes... (8 Replies)
cat ~/text.xt | while read line
do
echo ${line} | perl -pe 's/(\d+)/localtime($1)/e'
done
how can i efficiently re-code the above?
also, no matter how i run this, i'm not getting the current/correct date. the contents of the "text.xt" looks like this:
SERVICES... (2 Replies)
Fighting UUOC
cat filename|while read line; do ...
with
sed 's/cat *\(*\) *|/<\1/g'
I found that while loops are converted to
<filename while read line; do ...
Syntax error!
Why syntax error? It would perfectly make sense.
Further, read the article how-would-you-like-your-loops-served-today... (5 Replies)
Discussion started by: MadeInGermany
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)
01-04-2014
Quest for the most useless command
