Hi All,
I didn't find any thread that match this question so I hope it's not redundant. I am totally new to Unix. I want to know what is the maximum length of the os-commandline in Unix. Will it cause any problem if I run any application whose total path length is much longer than 256... (2 Replies)
hi,
I am using solaris10. I have to write a bourne shell script, which copies files for the said destination path which is passed as an argument to the script.
it looks like this
myscript.sh /var/test -->destination path
now i would like to know what is the maximum length i can... (3 Replies)
Hi,
I need to create a file of record length more than 300 characters.
But in my unix box, i am able to create a file only with a maximum of 256 characters per record.
Is there anyway i can create a file with more than 300 characters in this case?
Or How to increase the maximum record... (1 Reply)
Hi,
I wanted to know what is the maximum length of command which can be run on a bourne (sh) shell? Where can I find that information? Is it different for different OS flavors?
Please help.
Thanks,
Vineet (10 Replies)
Is there a maximum length for a shell script command? How can I detect that in my OS?
For example, if I have something like:
command A | command B | command C | awk '{print $1 $2 $3 $4 $5}'
then can we break the commands and also the arguments inside awk ?
Thanks (11 Replies)
How can I change the maximum length of a programming line in fortran and C (specifically in fortran 77)?
Seems the default maximum length is 72 in fortran 77.
Thanks. (4 Replies)
Discussion started by: hbar
4 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)