09-23-2008
10 More Discussions You Might Find Interesting
1. Filesystems, Disks and Memory
Hello!
How I can increase or decrease predefined pipe buffer size?
System FreeBSD 4.9 and RedHat Linux 9.0
Thanks! (1 Reply)
Discussion started by: Jus
1 Replies
2. Shell Programming and Scripting
Hi,
Can the cd command be invoked using pipes???
My actual question is slightly different. I am trying to run an executable from different folders and the path of these folders are obtained dynamically from the front end. Is there a way in which i can actually run the executable... (2 Replies)
Discussion started by: Sinbad
2 Replies
3. UNIX for Dummies Questions & Answers
im trying to figure out how to do the following:
using pipes to combine grep and find commands to print all lines in files that start with the letter f in the current directory that contain the word "test" for example?
again using pipes to combine grep and find command, how can I print all... (1 Reply)
Discussion started by: ez45
1 Replies
4. UNIX for Advanced & Expert Users
Hi all,
I tried the following command
$ find / -name xyx | ls -l
so logically it should show the listing of directory xyz , assuming there's only one instance of xyz . But the above command shows the listing of current directory instead.
I got the desired result using it in the... (4 Replies)
Discussion started by: bijeet_sunny
4 Replies
5. Programming
Hello all, I am trying to learn more about programming Unix pipes in C.
I have created a pipe that does od -bc < myfile | head
Now, I am trying to create od -bc < myfile | head | wc
Here is my code, and I know I might be off, thats why I am here so I can get some clarification.
#include... (1 Reply)
Discussion started by: petrca
1 Replies
6. Shell Programming and Scripting
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)
Discussion started by: tokland
10 Replies
7. Programming
problem solved. (1 Reply)
Discussion started by: superfons
1 Replies
8. Programming
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
9. Programming
Hi!
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:
if(pipe(client1r)<0){
perror("pipe");
}
... (1 Reply)
Discussion started by: serpens11
1 Replies
10. Shell Programming and Scripting
I already manage to get the output that i want.. but wat if removing all the pipes and convert it 1 liner with less pipes. My command below can get the ouput that i want. i just want to remove the pipes or less pipes.
#cat file1
us-west-2a running i-3397a421... (2 Replies)
Discussion started by: kenshinhimura
2 Replies
PIPE(2) System Calls Manual PIPE(2)
NAME
pipe - create an interprocess communication channel
SYNOPSIS
pipe(fildes)
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 4096 bytes of data are buffered before the writing process is suspended. A read
using the descriptor fildes[0] will pick up the data.
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.
Pipes are really a special case of the socketpair(2) call and, in fact, are implemented as such in the system.
A signal 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.
[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), socketpair(2)
BUGS
Should more than 4096 bytes be necessary in any pipe among a loop of processes, deadlock will occur.
4th Berkeley Distribution August 26, 1985 PIPE(2)