03-25-2009
The third option to open() - which is shown in man pages as "..." is only used when a new file is being created. In your case you are opening an existing file as read only.
"..." is a way of saying that the number and types of the remaining arguments may vary. There may be none or there may be one or more.
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
What does the system call "dup" do?
What is the difference between dup and dup2
I have a fair idea of what it does but I am confused when its coming down to the exact details...
Please help me!:confused: (2 Replies)
Discussion started by: clickonline1
2 Replies
2. UNIX for Dummies Questions & Answers
Which system calls are made for operations cp and mv (2 Replies)
Discussion started by: gaurava99
2 Replies
3. UNIX for Dummies Questions & Answers
open, creat, read, write, lseek and close
Are they all primitive?
:confused:
*Another Question: is there a different between a system call, and an i/o system call? (2 Replies)
Discussion started by: PlunderBunny
2 Replies
4. Solaris
where can i find the differences in System calls between solaris and aix?
also is it possible to find a comprehensive list of them? (1 Reply)
Discussion started by: TECHRAMESH
1 Replies
5. UNIX Desktop Questions & Answers
Hi,
I'm new to UNIX system calls. Can someone share your knowledge as to how exactly system calls should be executed?
Can they be typed like commands such as mkdir on the terminal itself? Also, are there any websites which will show me an example of the output to expect when a system call like... (1 Reply)
Discussion started by: ilavenil
1 Replies
6. UNIX for Dummies Questions & Answers
Hi all,
I am new here .
I want to know about system call in detail.
As system calls are also function .How system identifies it.:) (2 Replies)
Discussion started by: vishwasrao
2 Replies
7. UNIX for Dummies Questions & Answers
Hello,
how would i be able to call ps in C programming?
thanks,
---------- Post updated at 01:39 AM ---------- Previous update was at 01:31 AM ----------
here's the complete system call, ps -o pid -p %d, getpit() (2 Replies)
Discussion started by: l flipboi l
2 Replies
8. UNIX for Dummies Questions & Answers
I'm currently studying for my exam, and is practicing with sample exam questions.
However there is a question asking "Name THREE UNIX Directory system calls" and the answer given is "opendir, closedir and readdir", however the next question ask "Why is a write directory system call not included... (1 Reply)
Discussion started by: Izzy123
1 Replies
9. UNIX for Dummies Questions & Answers
Hello...
I'm trying to setup a cronjob to record system data using glance at certain times of the day. My question is, how would one export the "Global System Calls" information to a file? Below is the command I have been using and it works to export CPU information.
glance -f ... (0 Replies)
Discussion started by: fumus
0 Replies
10. UNIX for Dummies Questions & Answers
Hi i am very new to programming in UNIX and don't understand the difference between a system call and a normal function call. Also can I implement system calls from within a program? If so could someone please give me an example of a system call from within a program. Lastly, when creating a... (1 Reply)
Discussion started by: bjhum33
1 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)