getting the return from forked child process to parent in C++
This needs to work on HPUX and Linux.
I do a fork and create a child process. During execution of the child process, it is possible child become lost or get killed. That is the reason why I create the child process. However if the child process doesnt get killed, I do want to know the return value(return_I_want_to_save). Towards the end, I make sure all children gets killed anyway.
I cant seems to find a way to do this. Any help would be highly appropriated. This is not a home work problem. I am an intern.
Hi everybody,
I'm trying to understand how a parent and child processes interact.
This function( below) basically measures the fork time from the perspective of the parent only.
what i would like to know is how to measure the time from the perspective of parent and child (ie: inserting... (0 Replies)
Hi,
From within my C++ program, I fork a child process and execl an ftp session (solaris), like this :
std::string szStartCmd = "ftp -i -n -v 192.168.149.31";
int nExecRes = execl("/bin/sh", "sh", "-c", szStartCmd.c_str(), (char *)0);
I use 2 pipes to communicate between my... (7 Replies)
I have two shell scripts : A.sh and B.sh
A.sh
echo "In A"
exec B.sh
echo "After B"
B.sh
echo "In B"
The output is : In A
In B
I want the output : In A
In B
After B (4 Replies)
Hi All,
I have two ksh script. 1st script calls the 2nd script and the second script calls an 'C' program.
I want 1st script to wait until the 'C' program completes.
I cant able to get the process id for the 'C' program (child process) to make the 1st script to wait for the second... (7 Replies)
Hey all, I need to launch a script from within 2 other scripts that can run independently of the two parent scripts... Im having a hard time doing this, if anyone knows how please let me know.
More detail.
ScriptA (bash), ScriptB (ksh), ScriptC (bash)
ScriptA, launches ScriptB
ScirptB,... (7 Replies)
Hi,
I have a script that calls other scripts/commands which may or may not spawn other process.
From my understanding, when I do a ps -ef, the highest numbered process ID is supposed to be the parent ID of all the other related child processes, is this correct?
In most or all... (3 Replies)
Hi, i want that the parent process start before the child, this code doesn't work,
if the child start before the parent it wait for signal, then the father send the signal SIGALRM and the child catch it and call printf;
else the father call printf and send the signal to the child that call its... (1 Reply)
Hello, everyone.
Here's a program:
pid_t pid = fork();
if (0 == pid) // child process
{
execvp ...;
}
I send a signal (such as SIGINT) to the parent process, the child process receive the signal as well as the parent process.
However I don't want to child process to receive the... (7 Replies)
Hi everyone
i am very new to linux , working on bash shell.
I am trying to solve the given problem
1. Create a process and then create children using fork
2. Check the Status of the application for successful running.
3. Kill all the process(threads) except parent and first child... (2 Replies)
Hello everyone,
I am a complete newbie to UNIX. I am using Debian LXDE 64-bit. I have a question regarding the child and parent process communication. According to wikipedia.org and various other sources, when a child process exits it sends the SIGCHLD signal to its parent... (1 Reply)
Discussion started by: sreyan32
1 Replies
LEARN ABOUT ULTRIX
fork
fork(2) System Calls Manual fork(2)Name
fork - create a new process
Syntax
#include <sys/types.h>
#include <unistd.h>
pid = fork()
pid_t pid;
Description
The system call causes creation of a new process. The new process (child process) is an exact copy of the calling process except for the
following:
o The child process has a unique process ID.
o The child process has a different parent process ID (that is, the process ID of the parent process).
o The child process has its own copy of the parent's descriptors. These descriptors reference the same underlying objects, so that, for
instance, file pointers in file objects are shared between the child and the parent, so that a on a descriptor in the child process
can affect a subsequent read or write by the parent. This descriptor copying is also used by the shell to establish standard input
and output for newly created processes as well as to set up pipes.
o The child processes resource utilizations are set to 0. For further information, see
Return Values
Upon successful completion, returns a value of 0 to the child process and returns the process ID of the child process to the parent
process. Otherwise, a value of -1 is returned to the parent process, no child process is created, and the global variable errno is set to
indicate the error.
Diagnostics
The system call fails and no child process are created under the following conditions:
[EAGAIN] The system-imposed limit {PROC_MAX} on the total number of processes under execution would be exceeded.
[EAGAIN] The system-imposed limit {CHILD_MAX} on the total number of processes under execution by a single user would be exceeded.
[ENOMEM] There is insufficient swap space for the new process.
See Alsoexecve(2), wait(2)fork(2)