Sponsored Content
Top Forums UNIX for Dummies Questions & Answers trying to understand rationale of unix stream i/o concept Post 302333217 by kaychau on Saturday 11th of July 2009 05:19:32 PM
Old 07-11-2009
trying to understand rationale of unix stream i/o concept

I am an entry level programmer with no formal training in computer science. I am trying to enhance my conceptual knowledge about operating systems in general.

I have been using the C programming language on Linux systems for some time and have used the traditional unix stream I/O APIs. The introductory material in books and on the web, typically introduce the unix stream I/O model as "basic unix I/O model is a stream of bytes which can be accessed sequentially or randomly". I understand this part, but I am unable to visualize how else would one access the data. Were the I/O models different before the I/O stream model came in to existence? Are there models in current computing paradigm which are different from the stream I/O. I will appreciate if some can help me visualize both the stream I/O model vs other models (if they exist or existed). Pros-Cons will be a great addition too.

In addition, I came across the following statement on the web (I/O System)

"The basic model of the UNIX I/O system is a sequence of bytes that can be accessed either randomly or sequentially. There are no access methods and no control blocks in a typical UNIX user process."

I do not understand the last statement - what are access methods and control blocks in the context of I/O?

Thanks
Kay
 

9 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Having difficulty with UNIX concept. Please help!

Hi, I would be very happy if someone could help me please. I am relatively new to UNIX, and still learning. My understanding of things are: Say I have a PC running Windows. This machine has a name. If I have 10 PC's, then I have 10 names, one for each PC. Each PC is independent of the other.... (4 Replies)
Discussion started by: ALon
4 Replies

2. UNIX for Advanced & Expert Users

don't understand the unix script

if {"$my_ext_type" = MAIN]; then cd $v_sc_dir Filex.SH $v_so_dir\/$v_fr_file Can somebody tell me what does this suggest. I am pretty new to unix and I am getting confused. What i understood from here is If we have a file extension name as MAIN which we have then we change the directory to... (1 Reply)
Discussion started by: pochaman
1 Replies

3. Shell Programming and Scripting

[Video stream] network stream recording with mplayer

Hi I used this command: mplayer http://host/axis-cgi/mjpg/video.cgi -user root -passwd root \ -cache 1024 -fps 25.0 -nosound -vc ffh264 \ -demuxer 3 -dumpstream -dumpfile output.avi It's ok but... Video Playing is very fast! Why? Is it a synch problem? What parameter I have to use for... (1 Reply)
Discussion started by: takeo.kikuta
1 Replies

4. Shell Programming and Scripting

Regarding Mail concept in unix

Hi, I am new to this mail concept in unix. i have requirement to read the mail from mailbox. Now to get the mail where i have to configure the mail id and also the mail server. Kindly suggest me. Thanks in advance. (3 Replies)
Discussion started by: krishna_gnv
3 Replies

5. Shell Programming and Scripting

Understand a old unix shell script

Hi All, I have a unix old script i but i am not able to understand the few commands in it and what it does. below is the script. if ; then for F in $(find $DIR/. ! -name . -prune -name "DP_*.dat") do IN=${F##/*/} OUT='ORD'$(echo $IN | cut -c7-) exec.ksh $IN... (2 Replies)
Discussion started by: kam786sim
2 Replies

6. UNIX for Dummies Questions & Answers

Plan9 sed - rationale for limitations

Using the 9base port in {Net,Free}BSD, it appears that Plan 9's sed 1. restricts the max number of sed commands and thereby the length of sed scripts 2. does not recognise the \nn flag where nn is the number of a matched substring. See example below. Questions: 1. Why would they limit... (1 Reply)
Discussion started by: uiop44
1 Replies

7. What is on Your Mind?

What exactly is the concept of BITS in this unix.com forum?

Is there a detailed page on the explanation of concept behind BITS and score used in this forum. Just saw the index on my Banking page. (Clicked the Banking hyperlink below my profile name on the topmost right corner of this screen) Thanks in advance. (2 Replies)
Discussion started by: Manjunath B
2 Replies

8. Shell Programming and Scripting

Stream manipulation in UNIX shell scripting

i have a file something like this : start: 01:00:00 01:30:00 02:30:00 05:30:00 end: 01:13:00 02:00:00 02:40:00 05:45:00 and i want (end - start) total run time in below format: run: 00:13:00 00:30:00 00:10:00 00:15:00 (4 Replies)
Discussion started by: Acme
4 Replies

9. Red Hat

How to Understand the UNIX Time Format?

How to understand the unix time format as here i have pasted this is a unix time 1402565420 and its 3:00 PM here but its give this Output as long number How can i make it to understand format as i have 3:00 PM Normal time format <----3:00PM = 1402565420----> Unix Time Will Any one Explain to... (4 Replies)
Discussion started by: babinlonston
4 Replies
ANLDP(1)						      General Commands Manual							  ANLDP(1)

NAME
anldp - implementation of Davis-Putnam propositional satisfiability procedure SYNOPSIS
anldp [options] < input-file > output-file DESCRIPTION
This manual page documents briefly the anldp command. anldp is an implementation of a Davis-Putnam procedure for the propositional satisfiability problem. anldp exposes the procedure used by mace2(1) to determine satisfiability. anldp can also take statements in first-order logic with equality and a domain size n then search for models of size n. The first-order model-searching code transforms the statements into set of propositional clauses such that the first- order statements have a model of size n if and only if the propositional clauses are satisfiable. The propositional set is then given to the Davis-Putnam code; any propositional models that are found can be translated to models of the first-order statements. The first-order model-searching program accepts statements only in a flattened relational clause form without function symbols. OPTIONS
-s Perform subsumption. (Subsumption is always performed during unit preprocessing.) -p Print models as they are found. -m n Stop when the nth model is found. -t n Stop after n seconds. -k n Allocate at most n kbytes for storage of clauses. -x n Quasigroup experiment n. -B file Backup assignments to a file. -b n Backup assignments every n seconds. -R file Restore assignments from a file. The file typically contains just the last line of a backup file. Other input, in particular the clauses, must be given exactly as in the original search. -n n This option is used for first-order model searches. The parameter n specifies the domain size, and its presence tells the program to read first-order flattened relational input clauses instead of propositional clauses. SEE ALSO
formed(1), mace2(1), otter(1). Full documentation for anldp is found in /usr/share/doc/mace2/anldp.{html,ps.gz}. AUTHOR
anldp ws written by William McCune <otter@mcs.anl.gov> This manual page was written by Peter Collingbourne <pcc03@doc.ic.ac.uk>, for the Debian project (but may be used by others). November 5, 2006 ANLDP(1)
All times are GMT -4. The time now is 11:07 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy