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1. Shell Programming and Scripting
HI i would like to know how i can simulate a shell scripts for my requirement.
example
Server name child Process id Parent Process id
Vpesh 16013 15637
Server name child Process id Parent Process id
Vpesh 16014 15637
Server name child... (1 Reply)
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2. Shell Programming and Scripting
Hi everyone
i am very new to linux , working on bash shell.
I am trying to solve the given problem
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3. Emergency UNIX and Linux Support
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.
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4. Programming
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;
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Discussion started by: blob84
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5. UNIX for Dummies Questions & Answers
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)
Discussion started by: newbie_01
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6. Programming
Hi guys, I'm having some problem here, I'm studying pipes, and i want to create a shell in C and at this point a don't want to use semaphores, instead I want to use tricks. Straight to the doubt: I've a parent and a child process, and both of them has some code to execute, and the child process... (5 Replies)
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7. Shell Programming and Scripting
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.
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8. Shell Programming and Scripting
Hi
I want to do something that might sound strange.
I have a code that in written in C and is executed at startup (it's a custom process). It occasionally calls some bash scripts.
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9. UNIX for Advanced & Expert Users
Hi
I am trying to see if there are some options in ps command or if there is a shell script which basically shows you all the processes spawned by a parent process , then all the processes of its child processes and so on down the hierarchy may be like a tree structure. It might be a generic... (6 Replies)
Discussion started by: clifford
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10. Programming
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)
Discussion started by: tosa
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FORK(2) BSD System Calls Manual FORK(2)
NAME
fork -- create a new process
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#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 (parent process) except for
the following:
o The child process has a unique process ID.
o The child process has a different parent process ID (i.e., 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 an lseek(2) on a descriptor in the
child process can affect a subsequent read(2) or write(2) 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 process' resource utilizations are set to 0; see setrlimit(2).
In general, the child process should call _exit(2) rather than exit(3). Otherwise, any stdio buffers that exist both in the parent and child
will be flushed twice. Similarly, _exit(2) should be used to prevent atexit(3) routines from being called twice (once in the parent and once
in the child).
In case of a threaded program, only the thread calling fork() is still running in the child processes.
Child processes of a threaded program have additional restrictions, a child must only call functions that are async-signal-safe. Very few
functions are asynchronously safe and applications should make sure they call exec(3) as soon as possible.
RETURN VALUES
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:
[EAGAIN] The system-imposed limit on the total number of processes under execution would be exceeded. This limit is configuration-depen-
dent.
[EAGAIN] The limit RLIMIT_NPROC on the total number of processes under execution by this user id would be exceeded.
[ENOMEM] There is insufficient swap space for the new process.
SEE ALSO
execve(2), setrlimit(2), vfork(2), wait(2), pthread_atfork(3)
STANDARDS
The fork() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').
HISTORY
A fork() system call appeared in Version 6 AT&T UNIX.
BSD
June 10, 2004 BSD