can you please tell me what is the purpose of the following line:
Code:
sh -c /home/dir/script.sh || exit 33
what i am confused is the || is this an OR boolean, or it might have some other purpose.
do you know how this works ?
i believe the first to run is the /home/dir/script.sh but what throws me off is the exit 33 with ||
i have a lot of messages file in the var directory i want to delete
now i want to keep messages.1 to messages.10 and then delete everything else after 10 which is like 10 to 96
obviously i cant delete these files individual, can someone tell me the command to delete messages.11 to... (1 Reply)
Hello all:
I'm trying to use the tr command to change some text in a file, but it is not working as expected. Here's what I'm trying:
tr 'INVOIC01' 'INVOICZZ' < inputfile > outputfile
It looks to be changing not just the entire string, but any characters within. I just want to change the... (2 Replies)
What does 'directory=`pwd $1` ' mean, I know pwd is present working directory, so does that command take the present working directory of the directory the user is in depending on the varible ($1)? (2 Replies)
When I use the mv command like say, mv file1 ../, it will move file1 to the parent directory of my current working directory. But where would the file go if I do mv file ... (with 3 periods), where would this move file1? (4 Replies)
$ echo 2 * 3 > 5 is a valid inequality.
This will create a file in the current directory named '5' with the number '2' in it, the names of all the files in the current directory, followed by the number '3' and 'is a valid inequality.'
What I do not understand is why 'is a valid inequality' gets... (2 Replies)
I am going through the Unix Made Easy second edition book by John Muster. So far it's been very informative and I can tell it may be a bit out of date.
In one of the exercises it talks about the "sort" command and using it to sort column's of data etc. The "sort" command has changed a bit and... (1 Reply)
I am scratching my head right now. I am trying to archive a ton of files in a directory. I am attempting to tar them by year. On our development server if I type ls *_2008* it returns all of the files I am expecting to see. (The format of the filename includes xx_xx_xxx_2008-09-29_xxx.xxxx.xxxx)... (8 Replies)
Discussion started by: jmartin99
8 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)
09-05-2013
