Is there a way to know whether is pipe is opened in read or write mode.I mean is there any signal that is generated when a pipe is opened in read or write mode.
If you have some solution .please let me know ........ (2 Replies)
Hi,
Can any one please help me with this. Am struggling hard to get a solution.
I am doing telnet through a C program and getting the stdout file descriptor of the remote machine to pipe.
read() function is getting data, But whenl it receives SOH character ie. ^A ( Start of heading = Console... (2 Replies)
Could anyone tell me whats wrong whit this piping? the commands that they execute are correct. the command I am trying is ls|wc. Both processes go to the right if statement.
for(i=0;i<argc;i++){
if(i==0&&argc>1){//first command
if(pipe(pipa1)==-1)
... (2 Replies)
Hello !
I want to process a text file in order to extract desired data using sed and grep... Now I am facing a problem piping to grep... nothing happens..
The text consists of blocks of 3 lines that may (or not) contain the Desired data.
the desired data is on each 2... (4 Replies)
Is there a way I can do this:
search for text and replace line containing matched text with a different line?
For example:
"I want to replace text"
I want to search for replace and then change the line to
I am perplexed.
Hope that makes sense.
Thanks in advance. (4 Replies)
hi i am having issues with extra pipe.
i have a data file and i need to remove the extra pipe in the(example 4th and 7thline) in datafile. there are many other line and filed like this which i need to remove from files. The sample data is below:
270 31|455004|24/03/2010|0001235|72
271... (3 Replies)
Hi all,
Im trying to do a simple program which ask the user for a unix command with the arguments. The program fork and the two process communicate with pipes. The child process call execvp with the command and the father process read the result of the execvp via the pipe.
This program works... (11 Replies)
Hi,guys:
I want to use c to implement a pipe. For example:
ps auxwww | grep fred | more
I forked three child processes. Each is responsible for each command, and pipe to next one.
for(i=0;i<2;i++)
pipe(fd)
if(child==1) // child 1
{
close(1)
dup2(fd,1)
close(fd)
}... (3 Replies)
<tr><th align=right valign=top>Faulty_Part</th><td align=left valign=top>readhat version 6.0</td></tr> <tr><th align=right valign=top>Submit_Date</th><td align=left valign=top>2011-04-28 02:08:02</td></tr> .......(a long string)
I want to get all the field between "left valign=top>" and "... (2 Replies)
Hi Friends,
I am using a command that prints certain lines from a file.
For ex:
cat input
abc chr1 456
def chr1 789
ghi chr1 999
jjj chr1 777
jhk chr7 914
My command
awk '{if($2=="chr1" && $3>=456 && $3<=999) {print $0}}' OFS="\t" input
Output being printed is
abc chr1 456 (7 Replies)
Discussion started by: jacobs.smith
7 Replies
LEARN ABOUT MINIX
pipe
PIPE(2) System Calls Manual PIPE(2)NAME
pipe - create an interprocess communication channel
SYNOPSIS
#include <unistd.h>
int pipe(int fildes[2])
DESCRIPTION
The pipe system call creates an I/O mechanism called a pipe. The file descriptors returned can be used in read and write operations. When
the pipe is written using the descriptor fildes[1] up to PIPE_MAX bytes of data are buffered before the writing process is suspended. A
read using the descriptor fildes[0] will pick up the data.
PIPE_MAX equals 7168 under Minix, but note that most systems use 4096.
It is assumed that after the pipe has been set up, two (or more) cooperating processes (created by subsequent fork calls) will pass data
through the pipe with read and write calls.
The shell has a syntax to set up a linear array of processes connected by pipes.
Read calls on an empty pipe (no buffered data) with only one end (all write file descriptors closed) returns an end-of-file.
The signal SIGPIPE is generated if a write on a pipe with only one end is attempted.
RETURN VALUE
The function value zero is returned if the pipe was created; -1 if an error occurred.
ERRORS
The pipe call will fail if:
[EMFILE] Too many descriptors are active.
[ENFILE] The system file table is full.
[ENOSPC] The pipe file system (usually the root file system) has no free inodes.
[EFAULT] The fildes buffer is in an invalid area of the process's address space.
SEE ALSO sh(1), read(2), write(2), fork(2).
NOTES
Writes may return ENOSPC errors if no pipe data can be buffered, because the pipe file system is full.
BUGS
Should more than PIPE_MAX bytes be necessary in any pipe among a loop of processes, deadlock will occur.
4th Berkeley Distribution August 26, 1985 PIPE(2)