09-13-2010
Atomic Read and Write with stdio
hi guys.
can we use fread and fwrite with pipes to write data more than PIPE_BUF atomically since they lock FILE object until I/O operation finish?
9 More Discussions You Might Find Interesting
1. Programming
How can 'popen()' be used for reading and writing to opening pipe?
If i try 'popen("prog", "rw")'
and then put and get chars - it does
not work.
What is wrong? (1 Reply)
Discussion started by: szzz
1 Replies
2. Shell Programming and Scripting
I have tried to show the file name whose size is greater than 200 byte in current directory.
Please help me.
ls -l | tr -s " " " " | cut -f 5,9 -d " " >out.txt
#set -a x `cat out.txt`
i=0
`cat out.txt` | while
do
read x
echo $x
#re=200
j=0
if }" < "200" ]
then
echo $j
j=`expr $j... (2 Replies)
Discussion started by: rinku
2 Replies
3. Shell Programming and Scripting
I need to find all the files that have group Read or Write permission or files that have user write permission.
This is what I have so far:
find . -exec ls -l {} \; | awk '/-...rw..w./ {print $1 " " $3 " " $4 " " $9}'
It shows me all files where group read = true, group write = true... (5 Replies)
Discussion started by: shunter63
5 Replies
4. Programming
Hi all,
I have a problem with some read/write functions.
I have a .bin file which contains a lot of structures as follows:
struct alumno
{
char id;
char apellido1;
char apellido2;
char nombre;
float nota1p;
float nota2p;
float notamedia;
char photofilename;
};
What I have... (3 Replies)
Discussion started by: Attenea
3 Replies
5. IP Networking
Hi,
We have smb client running on two of the linux boxes and smb server on another linux system. During a backup operation which uses smb, read of a file was allowed while write to the same file was going on.Also simultaneous writes to the same file were allowed.Following are the settings in the... (1 Reply)
Discussion started by: swatidas11
1 Replies
6. IP Networking
hi
am newbie to unix and socket programing
I am trying to figuring out syntax for read and write
to send data from server to client and client can read it
I have to send two integers
write(newsockfd,buffer,"%d %d",x,y,0) writing from client where x and y are two integers..
... (7 Replies)
Discussion started by: karthik1238
7 Replies
7. Shell Programming and Scripting
I have got a file in following format:
AAAAAAA
BBBBBBBB
CCCCCCC
DDDDDDD
I am trying to read this file and out put it in following format:
AAAAAAA,BBBBBBB,CCCCCCC,DDDDDD
Preferred method is shell or Perl.
Any help appreciated. (11 Replies)
Discussion started by: Araoki
11 Replies
8. Shell Programming and Scripting
Hello Guys, How all are doing?
I have an issue in Unix and want help from all of you
I have a file in UNIX which it read by line by line , If at the end of line '0' is written the it should fetch that line into another file and change '0' to '1'
and If at the end of line '1' is written then it... (10 Replies)
Discussion started by: adisky123
10 Replies
9. Programming
Can someone help me to write this program in C in QNX?
Using the FIFO queues write a simple communication system consisting of programs write and read. The program write the parameters given strings enclosed in single quotes. These strings are written to the FIFO file. Reads the program read... (1 Reply)
Discussion started by: ebasse2
1 Replies
FREAD(3) BSD Library Functions Manual FREAD(3)
NAME
fread, fwrite -- binary stream input/output
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdio.h>
size_t
fread(void * restrict ptr, size_t size, size_t nmemb, FILE * restrict stream);
size_t
fwrite(const void * restrict ptr, size_t size, size_t nmemb, FILE * restrict stream);
DESCRIPTION
The function fread() reads nmemb objects, each size bytes long, from the stream pointed to by stream, storing them at the location given by
ptr.
The function fwrite() writes nmemb objects, each size bytes long, to the stream pointed to by stream, obtaining them from the location given
by ptr.
Mixing fread() and fwrite() calls without setting the file position explicitly using fsetpos(3) between read and write or write and read
operations will lead to unexpected results because of buffering the file pointer not being set to the expected position after each operation
completes. This behavior is allowed by ANSI C for efficiency and it will not be changed.
RETURN VALUES
The functions fread() and fwrite() advance the file position indicator for the stream by the number of bytes read or written. They return
the number of objects read or written. If size or nmemb is 0, the functions return 0 and the state of stream remains unchanged. If an error
occurs, or the end-of-file is reached, the return value is a short object count (or zero).
The function fread() does not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which
occurred. The function fwrite() returns a value less than nmemb only if a write error has occurred.
SEE ALSO
read(2), write(2)
STANDARDS
The functions fread() and fwrite() conform to ANSI X3.159-1989 (``ANSI C89'').
BSD
September 11, 2011 BSD