I ask this question since sometimes i run a time-consuming ftp in foreground and forget to use nohup ftp.sh & to put this work background and can still running after i log off.
Assume this ftp task have run 1 hour, and still 1 hour time to end,
i don't want to abort the ftp, first, i use ctrl+Z... (3 Replies)
i am creating children processes using fork system call
every child i create goes to sleep for random time.
when child stops running how can i catch his signal and turminate the child (2 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)
Hi All,
I facing a problem in handling signals between parent process communication. I am trying to send a signal(SIGINT) from child to parent. I am using kill function to do so and I am trying to read the signal using sigaction(). But the program is ending abruptly and I am not able to figure out... (4 Replies)
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)
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)
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)
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
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)