10-16-2005
Howto spawn multiple child processes and wait?
As far as I can tell, the bash wait command waits for a logical "AND" of all the child processes.
Assuming I am coding in C:
(1) What is the function I would use to create multiple bash child process running perl?
(2) What is the function I would use to reinvent the bash wait command so I could wait for a logical "OR" so my parent wakes up when the first child process dies?
Thanks,
Siegfried
10 More Discussions You Might Find Interesting
1. UNIX for Advanced & Expert Users
Hi
I have a shell script A which calls another 10 shell scripts which run in background. How do i make the parent script wait for the child scripts complete, or in other words, i must be able to do a grep of parent script to find out if the child scripts are still running.
My Code:
... (1 Reply)
Discussion started by: albertashish
1 Replies
2. Programming
I'm trying to make a program that will spawn multiple child processes then exit. I'm having trouble figuring out how to do this since after I fork, the child process begins running the program again (never ending).
int main(void){
for(int i = 0; i < 3; i++){
fork();
}... (1 Reply)
Discussion started by: cagney58
1 Replies
3. UNIX for Dummies Questions & Answers
I've been working on some scripts in which I spawn some background processes. I'd like to be able to limit the number of processes, but have my script spawn additional processes as previous tasks finish. So, let's say I have 20 tasks to complete. Any given task could take from 1 to 10 minutes. ... (7 Replies)
Discussion started by: treesloth
7 Replies
4. Shell Programming and Scripting
I am trying to find a list of files and writing it to a text file. Based on the machine performance the file writing will be slow at certain time.
The code to find file and redirecting the output to text file is on a shell script
/usr/bin/find $SEARCH_DIR -daystart \( \( -name 'KI*' -a... (4 Replies)
Discussion started by: nuthalapati
4 Replies
5. Programming
Hello. I want to make a child do some stuff,wait,then the parent does some stuff and then child does some stuff and waits again.I have made the following but it does not work.Can anybody help me?
pid1 = fork();
if (pid1 == -1)
{
perror("Can't create child\n");
... (18 Replies)
Discussion started by: Cuervo
18 Replies
6. Shell Programming and Scripting
Hi,
I have three files in my IN directory.Each file should be copied 25 times using for loop.Each file processing should run in parallel?How to spawn multiple processes in unix?Any help would be appreciated.
Thanks,
Liyakath (7 Replies)
Discussion started by: liyakathali
7 Replies
7. Shell Programming and Scripting
Let's say I start process A.sh, then start process B.sh. I call both of them in my C.sh
How can I make sure that B starts its execution only after A.sh finishes.
I have to do this in loop.Execution time of A.sh may vary everytime.
It is a parameterized script. (17 Replies)
Discussion started by: rafa_fed2
17 Replies
8. UNIX for Dummies Questions & Answers
Hello all,
I have a very basic question. I have a requirement where in, I have a main process which forks a child process, which execs and runs a c executable corresponding to a daemon. In the c executable corresponding to a daemon, as everyone does, I fork another child process, and as part of... (7 Replies)
Discussion started by: sai2krishna
7 Replies
9. Shell Programming and Scripting
Hi all,
I am starting mgen5 for sometime depends on input from a file, in a child process. now I want to make parent to wait in this child process till mgen5 finishes, or timeout happens.
could anyone please tell me how to make parent to wait in child process in shell script?
thanks... (2 Replies)
Discussion started by: girijajoshi
2 Replies
10. UNIX for Beginners Questions & Answers
Hi
I am facing a problem in my ksh.
My main script is calling 3 different child process in the background.
I am using wait to finish all and then submit another 3 child processes.
Now what i want is , whenever any one child process finishes ,i want to submit next one.so that parallel 3... (2 Replies)
Discussion started by: Sangu
2 Replies
LEARN ABOUT OPENSOLARIS
wait
wait(3C) Standard C Library Functions wait(3C)
NAME
wait - wait for child process to stop or terminate
SYNOPSIS
#include <sys/types.h>
#include <sys/wait.h>
pid_t wait(int *stat_loc);
DESCRIPTION
The wait() function will suspend execution of the calling thread until status information for one of its terminated child processes is
available, or until delivery of a signal whose action is either to execute a signal-catching function or to terminate the process. If more
than one thread is suspended in wait(), waitpid(3C), or waitid(2) awaiting termination of the same process, exactly one thread will return
the process status at the time of the target process termination. If status information is available prior to the call to wait(), return
will be immediate.
If wait() returns because the status of a child process is available, it returns the process ID of the child process. If the calling
process specified a non-zero value for stat_loc, the status of the child process is stored in the location pointed to by stat_loc. That
status can be evaluated with the macros described on the wait.h(3HEAD) manual page.
In the following, status is the object pointed to by stat_loc:
o If the child process terminated due to an _exit() call, the low order 8 bits of status will be 0 and the high order 8 bits will
contain the low order 7 bits of the argument that the child process passed to _exit(); see exit(2).
o If the child process terminated due to a signal, the high order 8 bits of status will be 0 and the low order 7bits will contain
the number of the signal that caused the termination. In addition, if WCOREFLG is set, a "core image" will have been produced;
see signal.h(3HEAD) and wait.h(3HEAD).
One instance of a SIGCHLD signal is queued for each child process whose status has changed. If wait() returns because the status of a child
process is available, any pending SIGCHLD signal associated with the process ID of that child process is discarded. Any other pending
SIGCHLD signals remain pending.
If the calling process has SA_NOCLDWAIT set or has SIGCHLD set to SIG_IGN, and the process has no unwaited children that were transformed
into zombie processes, it will block until all of its children terminate, and wait() will fail and set errno to ECHILD.
If a parent process terminates without waiting for its child processes to terminate, the parent process ID of each child process is set to
1, with the initialization process inheriting the child processes; see Intro(2).
RETURN VALUES
When wait() returns due to a terminated child process, the process ID of the child is returned to the calling process. Otherwise, -1 is
returned and errno is set to indicate the error.
ERRORS
The wait() function will fail if:
ECHILD The calling process has no existing unwaited-for child processes.
EINTR The function was interrupted by a signal.
USAGE
Since wait() blocks on a stopped child, a calling process wanting to see the return results of such a call should use waitpid(3C) or
waitid(2) instead of wait(). The wait() function is implemented as a call to waitpid(-1, stat_loc, 0).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |Async-Signal-Safe |
+-----------------------------+-----------------------------+
SEE ALSO
Intro(2), exec(2), exit(2), fork(2), pause(2), waitid(2), ptrace(3C), signal(3C), signal.h(3HEAD), waitpid(3C), wait.h(3HEAD),
attributes(5)
SunOS 5.11 9 Jun 2004 wait(3C)