I'm having problems with pipes... I need comunnications with childs processes and parents, but only one child can comunnicate with parent (first child), others childs can't.
A brief of code:
Results are:
First pipe (client1r) works correctly, but others pipe (client2r and client3r) doesn't works. I don't understant why doesn't works, because others pipes are exactly the same, and then I call another function (function client) passin the value.
I have a one line bat script run off a XP machine that tar's and compresses some files from a Sol 8 box. It goes something like this (a bit simplified)....
plink -pw <passwd> user@host "tar -cvf - -C / tmp/a_file | compress " > a_file.tar.Z
So this works....and it's worked many times. But now... (3 Replies)
I have written the following program. The function of this prog is to read data from a file(source.c) and write into another file(dest.c) using pipes. I have just written a line in the source file.Im able to compile and run the program without errors. But the data is not written onto the other... (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)
1. The problem statement, all variables and given/known data:
I have two files created from extracting data off of two CSV files, one containing class enrollment on a specific quarter and the other containing grades for that specific quarter. The Enrollment file generated contains course name,... (11 Replies)
Here is an example code that shows the issue I have:
#!/bin/bash
counter() {
seq 1000 | while read NUM; do
echo $NUM
echo "debug: $NUM" >&2
sleep 0.1 # slow it down so we know when this loop really ends
done
}
counter | grep --line-buffered "" | head -n1
... (10 Replies)
I'm using Sendmail 8.13.8 on a CentOS 5.5 vServer (Virtuozzo).
I'm using a loop in PHP to send a lot of HTML-mails via sendmail. Each mail is a mail with individual statistics for our users, so its not mass mailing, bcc is not an option.
It all works fine, but when I take a closer look there... (2 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)
I want to have a message send & receive through 2 half-duplex pipes
Flow of data
top half pipe
stdin--->parent(client) fd1--->pipe1-->child(server) fd1
bottom half pipe
child(server) fd2---->pipe2--->parent(client) fd2--->stdout
I need to have boundary structed message... (1 Reply)
Discussion started by: ouou
1 Replies
LEARN ABOUT ULTRIX
vfork
vfork(2) System Calls Manual vfork(2)Name
vfork - spawn new process in a virtual memory-efficient way
Syntax
pid = vfork()
int pid;
Description
The can be used to create new processes without fully copying the address space of the old process, which is inefficient in a paged envi-
ronment. It is useful when the purpose of would have been to create a new system context for an The system call differs from in that the
child borrows the parent's memory and thread of control until a call to or an exit (either by a call to or abnormally.) The parent process
is suspended while the child is using its resources.
The system call returns a value of zero (0) in the child's context and, later, the pid of the child in the parent's context.
The system call can normally be used just like It does not work, however, to return while running in the childs context from the procedure
which called because the eventual return from would then return to a nonexistent stack frame. Be careful, also, to call _exit rather than
exit if you cannot call because exit will flush and close standard I/O channels and thereby cause problems in the parent process's standard
I/O data structures. Even with it is wrong to call exit, because buffered data would then be flushed twice.
Restrictions
To avoid a possible deadlock situation, processes which are children in the middle of a are never sent SIGTTOU or SIGTTIN signals. Rather,
output or ioctls are allowed, and input attempts result in an end-of-file indication.
Diagnostics
Same as for
See Alsoexecve(2), fork(2), sigvec(2), wait(2)vfork(2)