unexpected values received when writing and reading from file
In the code below i try to write and read from a file, but i get unexpected results, like after writing i cannot open the file, and when reading the file the value entered earlier is not shown
Hi gurus
I am not a C programmer but I need to read and write files on a computer on LAN using IP address.
Suppose on a computer that has an IP 192.168.0.2
Any help or code example. I did in JAVA using URL, but do not know how to do in ANSI-C.
In java:
-------
URL url = new... (3 Replies)
Hi my prob statement is to create a new file or to append to the 1tst file the followign chages.
File 1: txt file.
portfolio No a b c d
abc 1 Any Any Any charString
cds 2 values values values charString
efd 3 can can can charString
fdg 4 come come come charString... (4 Replies)
Hi all,
I have the following shell script code which tries to sftp and writes the log into the log file.
TestConnection ()
{
echo 'Connection to ' $DESTUSERNAME@$DESTHOSTNAME
$SETDEBUG
if ]; then rm $SCRIPT ; fi
touch $SCRIPT
echo "cd" $REMOTEDIR >> $SCRIPT
echo "quit" >>... (10 Replies)
Hello everybody,
I'm trying to code a program which makes the following:
It sends an ARP request frame and when it gets the reply, extracts the IP address of source and writes it to a .txt file. This is gonna be done with many hosts (with a for() loop), so, the text file would look like... (2 Replies)
Hi All,
Please help me in writing data to a file in one row.
In database there is a column which contains large data which does not fit in the file in one row. The column contains list of paths. I want to write these paths to a file in one row.
Please find the code below writes :
... (2 Replies)
Need to develop a unix shell script for the below requirement and I need your assistance:
1) search for file.log and file.bad file in a directory and read them
2) pull out "Load_Start_Time", "Data_File_Name", "Error_Type" from log file
4) concatinate each row from bad file as... (3 Replies)
Hi
I am trying to extract information out of a file but keep getting grep cant open errors
the code is below:
#bash
#extract orders with blank address details
#
# obtain the current date
# set today to the current date ccyymmdd format
today=`date +%c%m%d | cut -c24-31`
echo... (8 Replies)
Hi All,
Here is my requirement. I am grepping through the log files and cutting some fields from the file to generate a csv file. Now I have to check if 2nd field is having some fixed value then with the help of 4th field I have to look in same log and run another grep command to retrieve the... (11 Replies)
I have a file like this,
1,a,saurav
2,b,rout
I want to show this file in a perl cgi page table and want to add a column which will contain a text box. There I will give some manual input, which will be written to the existing file(or a new file) in below format.
1|a|saurav|bangalore... (2 Replies)
Hello all
As part of my TUI - (line based) Text User Interface, i do have 2 commands to assist working with conf files.
Now, for me they work, but since i wrote them, i automaticly use them they way they should be used... you know what i mean. ;)
Anyway, they are designed to read 'simple'... (3 Replies)
Discussion started by: sea
3 Replies
LEARN ABOUT REDHAT
readv
READV(3) Linux Programmer's Manual READV(3)NAME
readv, writev - read or write data into multiple buffers
SYNOPSIS
#include <sys/uio.h>
int readv(int filedes, const struct iovec *vector,
size_t count);
int writev(int filedes, const struct iovec *vector,
size_t count);
DESCRIPTION
The readv() function reads count blocks from the file associated with the file descriptor filedes into the multiple buffers described by
vector.
The writev() function writes at most count blocks described by vector to the file associated with the file descriptor filedes.
The pointer vector points to a struct iovec defined in <sys/uio.h> as
struct iovec {
void *iov_base; /* Starting address */
size_t iov_len; /* Number of bytes */
};
Buffers are processed in the order vector[0], vector[1], ... vector[count].
The readv() function works just like read(2) except that multiple buffers are filled.
The writev() function works just like write(2) except that multiple buffers are written out.
RETURN VALUE
The readv() function returns the number of bytes or -1 on error; the writev() function returns the number of bytes written.
ERRORS
The readv() and writev() functions can fail and set errno to the following values:
EBADF fd is not a valid file descriptor.
EINVAL fd is unsuitable for reading (for readv()) or writing (for writev()).
EFAULT buf is outside the processes' address space.
EAGAIN Non-blocking I/O had been selected in the open() call, and reading or writing could not be done immediately.
EINTR Reading or writing was interrupted before any data was transferred.
CONFORMING TO
unknown
BUGS
It is not advisable to mix calls to functions like readv() or writev(), which operate on file descriptors, with the functions from the
stdio library; the results will be undefined and probably not what you want.
SEE ALSO read(2), write(2)GNU 1993-04-25 READV(3)