Greetings everyone, I need a bit of help in solving the following problem:
I'm given an array of numbers and I have to compute the sum of the array elements using n processes, and the inter process communication has to be done with pipes(one pipe, to be exact).
I managed to solve the problem by waiting for a random child to finish, reading the sum sent by the child through the pipe, and so on for the following children, and incrementing the final sum.
Now I have to solve it by reading the partial sums in one fell swoop, after all the children have finished, and I'm not sure as to how to save the entire information sent by the kids. I tried to use a for statement, but it failed, since all the information would be passed in one single element of the array, and offering only the address of the first element in the array failed as well.
Hi,
I have a program that runs two threads in stead of two processes. I want to use pipe to redirect the output of the first thread to the input of the second thread.
One thread is continuously writing to a pipe, and the other thread will read from the pipe.
How do I do that?
Is there... (2 Replies)
I know how to read and write if i have a forked process with only one child. However what is involved with reading and writing with many forked processes. Say one parent that forks 5 children, and needs to communicate with all 5 in half duplex.
int temp, counter=0;
do{
pipe(temp);
... (5 Replies)
Hi,
I will use below command for grep single string ("osuser" is search string)
ex: find . -type f | xarg grep -il osuser
but i have one more string "v$session"
here i want to grep in which file these two strings are present.
any help is appreciated,
Thanks in advance.
Gagan (2 Replies)
Hi,
I have a requirement with,
No~Dt~Notes
1~2011/08/1~"aaa
bbb
ccc
ddd
eee
fff
ggg
hhh"
Single column alone got splitted into multiple lines.
I require the output as
No~Dt~Notes
1~2011/08/1~"aaa<>bbb<>ccc<>ddd<>eee<>fff<>ggg<>hhh"
mean to say those new lines to be... (1 Reply)
Hi,
I am trying to convert multiple Unix pipe symbol or bar into single |. I have tried with the following sed statements, but, no success :(. I need it using sed only
echo "sed 's/\|\+/\|/g'
sed 's/*/\|/'
sed 's/\|*/|/'
sed -r 's/\|+/\|/'
However, the below awk code is working fine.... (4 Replies)
I have a script that finds all sffs and extracts them into .fastq file types. What I need to do is change the .fastq to .fasta using the below script. How can I change the input.fastq and output.fasta to mirror the file's name? Would I use an array and use the default iterator?
#!/bin/bash
... (3 Replies)
Single command to ls all the files inside a particular directory hierachy and output this to a file and open this in a vim file so that i can use gf command in vim to browse through all the files inside this hierachy.
eg :
dir1/dir2
and
dir1/dir3
dir2 and dir3 contain the files i need... (7 Replies)
The task I have to do is something along the lines "I receive some input and based on the first character I send it through pipe to one of the children to print".
The scheme it is based on is 1->2; 1->3; 1->4; 2 will print all the input that starts with a letter, 3 will print all the input that... (2 Replies)
Discussion started by: Ildiko
2 Replies
LEARN ABOUT OSX
tcl_waitpid
Tcl_DetachPids(3) Tcl Library Procedures Tcl_DetachPids(3)__________________________________________________________________________________________________________________________________________________NAME
Tcl_DetachPids, Tcl_ReapDetachedProcs, Tcl_WaitPid - manage child processes in background
SYNOPSIS
#include <tcl.h>
Tcl_DetachPids(numPids, pidPtr)
Tcl_ReapDetachedProcs()
Tcl_Pid
Tcl_WaitPid(pid, statusPtr, options)
ARGUMENTS
int numPids (in) Number of process ids contained in the array pointed to by pidPtr.
int *pidPtr (in) Address of array containing numPids process ids.
Tcl_Pid pid (in) The id of the process (pipe) to wait for.
int *statusPtr (out) The result of waiting on a process (pipe). Either 0 or ECHILD.
int options (in) The options controlling the wait. WNOHANG specifies not to wait when checking the process.
_________________________________________________________________DESCRIPTION
Tcl_DetachPids and Tcl_ReapDetachedProcs provide a mechanism for managing subprocesses that are running in background. These procedures
are needed because the parent of a process must eventually invoke the waitpid kernel call (or one of a few other similar kernel calls) to
wait for the child to exit. Until the parent waits for the child, the child's state cannot be completely reclaimed by the system. If a
parent continually creates children and doesn't wait on them, the system's process table will eventually overflow, even if all the children
have exited.
Tcl_DetachPids may be called to ask Tcl to take responsibility for one or more processes whose process ids are contained in the pidPtr
array passed as argument. The caller presumably has started these processes running in background and does not want to have to deal with
them again.
Tcl_ReapDetachedProcs invokes the waitpid kernel call on each of the background processes so that its state can be cleaned up if it has
exited. If the process has not exited yet, Tcl_ReapDetachedProcs does not wait for it to exit; it will check again the next time it is
invoked. Tcl automatically calls Tcl_ReapDetachedProcs each time the exec command is executed, so in most cases it is not necessary for
any code outside of Tcl to invoke Tcl_ReapDetachedProcs. However, if you call Tcl_DetachPids in situations where the exec command may
never get executed, you may wish to call Tcl_ReapDetachedProcs from time to time so that background processes can be cleaned up.
Tcl_WaitPid is a thin wrapper around the facilities provided by the operating system to wait on the end of a spawned process and to check a
whether spawned process is still running. It is used by Tcl_ReapDetachedProcs and the channel system to portably access the operating sys-
tem.
KEYWORDS
background, child, detach, process, wait
TclTcl_DetachPids(3)