Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Tool to simulate non-sequential disk I/O (simulate db file sequential read) in C POSIX
Top Forums Programming Tool to simulate non-sequential disk I/O (simulate db file sequential read) in C POSIX Post 302531771 by achenle on Friday 17th of June 2011 09:17:26 PM
Old 06-17-2011
Have at it. Don't forget - that's meant to be 64-bit code. It might work if you compile t with large-file compile flags/defines, but I'm not sure as I pretty much do nothing but 64-bit code any more.

I did forget to call srand48() to seed the random number generator. FWIW, something like this would work:

Code:
srand48( time( NULL ) );

On Solaris I usually like this as running something like the above C code over and over in a script can result in sequential runs getting the same "random" sequence when using time() as the seed because the seed value is the same:

Code:
srand48( gethrtime() );

I don't recall offhand if Linux has gethrtime() or an equivalent.

I also didn't try to test or even compile that code. There's a good chance I missed include files and put in something utterly brain dead.

And the location of the read isn't technically random because using the % operator means the beginning of the file will have a slightly larger chance of being selected because of the way it causes the full 64-bit random offset to wrap. But unless the file/device is HUGE it won't really matter - even multiple petabytes won't make the difference measurable.
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

inserting uniq sequential numbers at the start of the file

Hi Unix gurus, I have a file. I need to insert sequential number at the starting of the file. Fields are delimited by "|". I know the starting number. Example: File is as follows |123|4test|test |121|2test|test |x12|1test|test |vd123|5test|test starting number is : 120 ... (7 Replies)
Discussion started by: jingi1234
7 Replies

2. Programming

Reading special characters while converting sequential file to line sequential

We have to convert a sequential file to a 80 char line sequential file (HP UX platform).The sequential file contains special characters. which after conversion of the file to line sequential are getting coverted into "new line" or "tab" and file is getting distorted. Is there any way to read these... (2 Replies)
Discussion started by: Rajeshsu
2 Replies

3. Shell Programming and Scripting

Finding missing sequential file names

So, I've got a ton of files that I want to go through (ie something like 300,000), and they're all labeled sequentially. However I'm not 100% positive that they are all there. Is there any way of running through a sequence of numbers, checking if the file is in the folder, if not appending it... (2 Replies)
Discussion started by: Julolidine
2 Replies

4. Shell Programming and Scripting

how to scan a sequential file to fetch some of the records?

Hi I am working on a script which needs to scan a sequential file and fetch the row where 2nd column = 'HUB' Can any one help me with this... Thanks (1 Reply)
Discussion started by: manmeet
1 Replies

5. Shell Programming and Scripting

How to sca a sequential file and fetch some substring data from it

Hi, I have a task where i need to scan second column of seuential file and fetch first 3 digits of that column For e.g. FOLLOWING IS THE SAMPLE FOR MY SEQUENTIAL FILE AU_ID ACCT_NUM CRNCY_CDE THHSBC001 30045678 THB THHSBC001 10154267 THB THHSBC001 ... (2 Replies)
Discussion started by: manmeet
2 Replies

6. Shell Programming and Scripting

Sequential comparison (one row with file and so on)

Dear linux experts, I'd like to ask for your support, I've read some posts in this forum about files comparison but haven't found what I'm looking for. I need to create a sequential script to compare row-by-row one file with 34 similar files but without success so far. This is what I get: ... (2 Replies)
Discussion started by: Gery
2 Replies

7. Shell Programming and Scripting

sequential to line sequential

Hi I have a file sequential way i.e. written in contineous mode and the Record Seperator is AM from which the record is seperated .Now to process I have to make line sequential,and more over record length is not same it varies as per the input address, AM1234563 John Murray 24 Old streeet old... (5 Replies)
Discussion started by: vakharia Mahesh
5 Replies

8. UNIX for Dummies Questions & Answers

Inserting a sequential number into a field on a flat file

I have a csv flatfile with a few million rows. I need to replace a field (field number is 85) in the file with a sequential number. As an example, let's assume there are only 4 fields in the file: A,A,,32 A,A,,27 A,B,,43 C,C,,354 If I wanted to amend the 3rd field in this way my... (2 Replies)
Discussion started by: BristolSmithy
2 Replies

9. Shell Programming and Scripting

Read directories sequential based on timestamp

Hi, I have a directory structure like below Directoryname create time d1 12:00 d2 12:05 d3 12:08 I want to read the directories based on timestamp.That is oldest directory must be read first and kick off certain process. ... (7 Replies)
Discussion started by: chetan.c
7 Replies

10. Shell Programming and Scripting

Sequential Reading from two file in a loop

Hello All, I have two files with me file1.txt and file2.txt file1.txt has: 333 222 111 file2.txt has ccc bbb aaa ccc is related to 333 only, bbb is related to 222 only and aaa is related to 111 only. I have to get the values from each of the file and pass them in the URL... (3 Replies)
Discussion started by: ankur328
3 Replies

LEARN ABOUT SUSE

pk-debuginfo-install

PK-DEBUGINFO-INSTA(1)						  [FIXME: manual]					     PK-DEBUGINFO-INSTA(1)

NAME

       pk-debuginfo-install - Debugging Packages Installer

SYNOPSIS

       pk-debuginfo-install [--help] [--verbose] [--simulate] [--no-depends]

DESCRIPTION

       This manual page documents briefly the pk-debuginfo-install command.

       pk-debuginfo-install is the command line client for installing debuginfo packages.

WHY DO I NEED DEBUGINFO PACKAGES
?
       When a program crashes, it's often useful to send the developer a backtrace which contains symbol names and variable contents, rather than
       memory addresses. To make this possible, extra packages called debug packages can be installed.

OPTIONS

       This program follows the usual GNU command line syntax, with long options starting with two dashes (`-'). A summary of options is included
       below.

       --help
	   Show summary of options.

       --noninteractive
	   Do not be interactive and skip the confirmation before the packages are installed.

       --verbose
	   Show extra debugging information.

       --simulate
	   Don't actually install any packages, only simulate what would be installed.

       --no-depends
	   Do not scan for, or install dependencies of the core packages.

       --quiet
	   Do not display information or progress to the terminal.

RETURN VALUES

       0
	   Success, at least one package was installed

       1
	   Failed with miscellaneous internal error.

       3
	   Failed to get software sources list.

       4
	   Failed to enable software sources.

       5
	   Failed as nothing to do.

       6
	   Failed to find dependant packages.

       7
	   Failed to install.

       8
	   Failed to disable software sources.

SEE ALSO

       pkmon (1).  pkcon(1).

AUTHOR

       This manual page was written by Richard Hughes richard@hughsie.com.

COPYRIGHT

       Copyright (C) 2009 Richard Hughes

[FIXME: source] 						   29 July,2009 					     PK-DEBUGINFO-INSTA(1)
All times are GMT -4. The time now is 05:41 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy