Here we are trying to get PID of a child process in parent process. So I believe, it can be done only if child process runs in background. If process runs in foreground, ps command will execute only after child process is completed and then PID can't be obtained.
sleep is used to avoid cases when child process make take a while to get started.
~Others, Please correct if anything wrong here.
Last edited by anurag.singh; 12-21-2010 at 12:47 PM..
hi,
I am new ot unix. So, can i write a shell(c shell or korn shell) program to access internet? I mean if I run the program, it can access specified url and then copy the html to a file? Can anyone help me? And how can make the program runs every 1 hr?
new comer (2 Replies)
Hi,
i want to write a script that executes a program (exec?) .
this program then requires a filename as input.
how do i give it this input in the script so the program will be complete run and close by the script.
e.g.
exec prog.exe
program then asks for filename
"enter filename:"... (1 Reply)
Hi,
I am a complete newbie for unix. I have just installed mysql on my MAC. I was wondering every time I wanted to use mysql I had to ./mysql or sh mysql everytime on /usr/local/bin/mysql/bin. How can I execute the mysql program without using ./ or sh. I chmod +x already. And what do I have to... (3 Replies)
Hi All,
well , i am facing this problem.. i have tried a few sample codes but there isn't any solution . could anyone please give a sample code as of how to do this...
Please see the below details...and read the details carefully.
I have written some code, logic is
1)from... (4 Replies)
Hello,
I have a c program executable which I need to run inside a shell script.
But the c program runs in a subshell because of which all the actions done by the c program is not available to the current shell.
Is there any way to execute a C program binary executable in the current shell? (4 Replies)
My professor gave me a code with no errors.
When I compile it's fine, it doesn't show any errors, but when I try to execute it shows this:
line 3: syntax error near unexpected token '('
line 3: 'int main()'
I searched through the Internet but I couldn't find any solution. Please!!!... (1 Reply)
Hi there,
When I am trying to execute any shell script.
The shell script only execute line 1 and I notice that the rest o the program was not executed. Please advise.
# bash +x vmscript-4.sh
Even when I enter this command there is not output.
sudo su
cd /tmp
cp... (2 Replies)
Discussion started by: alvinoo
2 Replies
LEARN ABOUT MINIX
fork
FORK(2) System Calls Manual FORK(2)NAME
fork - create a new process
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
pid_t fork(void)
DESCRIPTION
Fork causes creation of a new process. The new process (child process) is an exact copy of the calling process except for the following:
The child process has a unique process ID.
The child process has a different parent process ID (i.e., the process ID of the parent process).
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 an lseek(2) 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.
The child starts with no pending signals and an inactive alarm timer.
RETURN VALUE
Upon successful completion, fork 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.
ERRORS
Fork will fail and no child process will be created if one or more of the following are true:
[EAGAIN] The system-imposed limit on the total number of processes under execution would be exceeded. This limit is configuration-
dependent. (The kernel variable NR_PROCS in <minix/config.h> (Minix), or <minix/const.h> (Minix-vmd).)
[ENOMEM] There is insufficient (virtual) memory for the new process.
SEE ALSO execve(2), wait(2).
3rd Berkeley Distribution May 22, 1986 FORK(2)