I'm trying to follow a script and I see it begins with this:
What does $# mean? I found out that $1 refers to the shell environment and the last argument that was entered or passed in the previous command. I couldn't find $# though. I believe this is just some sort of error checking saying "if something isn't present then stop here".
zsh 4.3.4% cat file
ACFCFACCACARCSHFARCVJVASTVAJFTVAJVGHBAJ
zsh 4.3.4% cat file1
A
C
F
R
zsh 4.3.4% <file1 while read;do printf "%s=%d\n" "$REPLY" "${#$(<file)//}";done
A=9
C=7
F=4
R=2
That was the previous post.
But , can anybody can explain me in detail about this line
zsh... (2 Replies)
this is the mksys b script....
can anyone explain .. what # and 1 in if condition
this is the first line of the script... it is not from middle of the script....
if
then
echo "Not enough parameters, need a client name for mksysb"
Usage="Usage: $0 <client name>"
... (2 Replies)
if
then
echo "Syntax: $0 <sid> <COLD/HOT> <DEST>"
exit
fi
if --------------what does this mean???
echo "Syntax: $0 <sid> <COLD/HOT> <DEST>"---pls explain this as well (2 Replies)
hi all i have an example i want one help me to understand cause i tried to test it but almost fail and i don't know how can i solve this problem " the main idea to read from two files and replace something from one to another " but i don't understand why it fail all time
$ cat main.txt... (4 Replies)
1. The problem statement, all variables and given/known data:
I have a retake assignment to complete for my computer networks and OS class. This isn't really my area, had I known last year I could have swapped it for a different module I would have done so. I'm determined to get through it... (6 Replies)
Can someone do me a favour and explain the following for me:
((r=$RANDOM%$n+1))
I know what $RANDOM does but what is % sign and what does it do with %$n+1? (2 Replies)
Hi friends! I'm learning UNIX and I have a small question. Working with Shell, i put the name of one executable (in c language) + one number and it says this:
$ gcc misterioso_4.c
$ ./misterioso_4 6
got: ,
I can not find an answer in the manual because I havent applied any variable.... (5 Replies)
Discussion started by: dakota
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)