I need to write a program which creates some n number of processes first and also creates a fifo for each of them, then it connects to the server and..
I tried creating these processes with fork() in a for loop but it doesn't print out what i write inside the child..
Hey all. I recently ported a multithreaded program from WinNT to LINUX using pthreads. Everything works fine, except that it turns out the drivers for the hardware I'm working with aren't thread safe. So, now I have to find a way to make this multi-process instead of multi-threaded.
I just... (1 Reply)
I need a quick script that will serve as a sort of "real time monitor" for watching some log files. I am using Bourne shell in HP-UX 10.20. I have basically created a script that never ends, unless of course I manually terminate it. Here's the script (it's called qhistory):
clear
echo "REAL... (3 Replies)
hello,
Every time i use fork() in the for loop, my college network(which i work in) either gets slow or hangs up.Can any 1 explain why it is so?
Of course there is no use of doing it though. But still i want to clear my doubt.
Thanks (2 Replies)
I have a parent that is passing data to child A and then child A has to process it and pass to child B. I am able to pass the data to child A but am not able to pass it to child B. Child B seems to only be receiving the last data instead of the whole data.
I saw one example in a book but it uses... (1 Reply)
hai,
i am doing my masters degree in computers.please any one tell me about
fork(),semaphores,mutex,messaging queues,messaging using pipes ,and msgget(),msgrecv() funtions
in ipc programming .
i have exam on that i have a book but in that they not given clearly.
hope u will
... (2 Replies)
Hi! I'm trying to write this program: in my intentions it should get a message and send it to a second process (pid_upost), then to a third process (pid1, pid2, pid3, depending on the choice made when a new message is inserted). This program should write the message in a file (message1, message2 or... (1 Reply)
I was asked to look into a problem with a Sun Netra 440 in another department. On the server in question, the relevant 'uname -a' information is, "SunOS host1 5.9 Generic_118558-16 sun4u sparc SUNW,Netra-440". That information aside, while the other admin is logged into the ALOM, these errors are... (0 Replies)
I am trying to ping through a list of devices in parallel.
When the code below is executed, I enter a infinite loop.
I want to used the number of lines in the file as my boundry.
I am a perl rookie and just cant see whats wrong.
would appreciate help ...
use Net::Ping;
#
$filename... (0 Replies)
Hello people.
I'm trying to do something like a search engine.
Server runs in the background by using ./server & which has data from a textfile stored in an array.
Client then runs by using ./client
It will then prompt "Search for:"
For example, if I searched for Products called Instant... (0 Replies)
Hi Experts,
Need your help for checking te interprocess communications settings on HP-UX box.
Using ipcs command I am able to view Message queue,semapohores etc, but from that output I m not able to understand how to determine if there is any issue with ipc settings and how to resolve that? (1 Reply)
Discussion started by: sai_2507
1 Replies
LEARN ABOUT V7
waitpid
waitpid(3C) Standard C Library Functions waitpid(3C)NAME
waitpid - wait for child process to change state
SYNOPSIS
#include <sys/types.h>
#include <sys/wait.h>
pid_t waitpid(pid_t pid, int *stat_loc, int options);
DESCRIPTION
The waitpid() 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 waitpid(), wait(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 waitpid(), return
will be immediate.
The pid argument specifies a set of child processes for which status is requested, as follows:
o If pid is equal to (pid_t)-1, status is requested for any child process.
If pid is greater than (pid_t)0, it specifies the process ID of the child process for which status is requested.
o If pid is equal to (pid_t)0 status is requested for any child process whose process group ID is equal to that of the calling
process.
o If pid is less than (pid_t)-1, status is requested for any child process whose process group ID is equal to the absolute value of
pid.
One instance of a SIGCHLD signal is queued for each child process whose status has changed. If waitpid() returns because the status of a
child process is available, and WNOWAIT was not specified in options, 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 waitpid() will fail and set errno to ECHILD.
If waitpid() returns because the status of a child process is available, then that status may be evaluated with the macros defined by
wait.h(3HEAD) If the calling process had specified a non-zero value of stat_loc, the status of the child process will be stored in the
location pointed to by stat_loc.
The options argument is constructed from the bitwise-inclusive OR of zero or more of the following flags, defined in the header
<sys/wait.h>:
WCONTINUED The status of any continued child process specified by pid, whose status has not been reported since it continued, is also
reported to the calling process.
WNOHANG The waitpid() function will not suspend execution of the calling process if status is not immediately available for one of
the child processes specified by pid.
WNOWAIT Keep the process whose status is returned in stat_loc in a waitable state. The process may be waited for again with identi-
cal results.
WUNTRACED The status of any child processes specified by pid that are stopped, and whose status has not yet been reported since they
stopped, is also reported to the calling process. WSTOPPED is a synonym for WUNTRACED.
RETURN VALUES
If waitpid() returns because the status of a child process is available, it returns a value equal to the process ID of the child process
for which status is reported. If waitpid() returns due to the delivery of a signal to the calling process, -1 is returned and errno is set
to EINTR. If waitpid() was invoked with WNOHANG set in options, it has at least one child process specified by pid for which status is
not available, and status is not available for any process specified by pid, then 0 is returned. Otherwise, -1 is returned and errno is
set to indicate the error.
ERRORS
The waitpid() function will fail if:
ECHILD The process or process group specified by pid does not exist or is not a child of the calling process or can never be in
the states specified by options.
EINTR The waitpid() function was interrupted due to the receipt of a signal sent by the calling process.
EINVAL An invalid value was specified for options.
USAGE
With options equal to 0 and pid equal to (pid_t)-1, waitpid() is identical to wait(3C). The waitpid() function is implemented as a call
to the more general waitid(2) function.
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), sigaction(2), ptrace(3C), signal(3C), siginfo.h(3HEAD), wait(3C), waitpid(3C),
wait.h(3HEAD), attributes(5), standards(5)SunOS 5.10 19 Jun 2003 waitpid(3C)
09-01-2010
