Sponsored Content
Top Forums Shell Programming and Scripting Using System calls without compilation Post 302142567 by porter on Saturday 27th of October 2007 09:19:43 PM
Old 10-27-2007
Quote:
Originally Posted by yamsin789
My program need to call some system calls such as fork etc...
With a shell script using the "&" causes a fork without wait.

eg

Code:
#!/bin/sh

run_this_as_a_child()
{
     ps
}

echo parent is $$

run_this_as_a_child &

echo parent is $$, child was $!

wait

Perhaps Perl may be more what you want.
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

System Calls

What does the system call "dup" do? What is the difference between dup and dup2 I have a fair idea of what it does but I am confused when its coming down to the exact details... Please help me!:confused: (2 Replies)
Discussion started by: clickonline1
2 Replies

2. UNIX for Dummies Questions & Answers

System calls for cp and mv

Which system calls are made for operations cp and mv (2 Replies)
Discussion started by: gaurava99
2 Replies

3. UNIX for Dummies Questions & Answers

System calls?

open, creat, read, write, lseek and close Are they all primitive? :confused: *Another Question: is there a different between a system call, and an i/o system call? (2 Replies)
Discussion started by: PlunderBunny
2 Replies

4. Solaris

System calls ?

where can i find the differences in System calls between solaris and aix? also is it possible to find a comprehensive list of them? (1 Reply)
Discussion started by: TECHRAMESH
1 Replies

5. UNIX Desktop Questions & Answers

Using system calls

Hi, I'm new to UNIX system calls. Can someone share your knowledge as to how exactly system calls should be executed? Can they be typed like commands such as mkdir on the terminal itself? Also, are there any websites which will show me an example of the output to expect when a system call like... (1 Reply)
Discussion started by: ilavenil
1 Replies

6. Programming

System calls

why user is not able to switch from user to kernel mode by writing the function whose code is identical to system call. (1 Reply)
Discussion started by: joshighanshyam
1 Replies

7. BSD

system calls

what is the functions and relationship between fork,exec,wait system calls as i am a beginer just want the fundamentals. (1 Reply)
Discussion started by: sangramdas
1 Replies

8. UNIX for Dummies Questions & Answers

About system calls.

Hi all, I am new here . I want to know about system call in detail. As system calls are also function .How system identifies it.:) (2 Replies)
Discussion started by: vishwasrao
2 Replies

9. UNIX for Dummies Questions & Answers

system calls in C

Hello, how would i be able to call ps in C programming? thanks, ---------- Post updated at 01:39 AM ---------- Previous update was at 01:31 AM ---------- here's the complete system call, ps -o pid -p %d, getpit() (2 Replies)
Discussion started by: l flipboi l
2 Replies

10. UNIX for Dummies Questions & Answers

System calls in UNIX

Hi i am very new to programming in UNIX and don't understand the difference between a system call and a normal function call. Also can I implement system calls from within a program? If so could someone please give me an example of a system call from within a program. Lastly, when creating a... (1 Reply)
Discussion started by: bjhum33
1 Replies
VFORK(2)						      BSD System Calls Manual							  VFORK(2)

NAME
vfork -- spawn new process in a virtual memory efficient way SYNOPSIS
#include <unistd.h> pid_t vfork(void); DESCRIPTION
Vfork() can be used to create new processes without fully copying the address space of the old process, which is horrendously inefficient in a paged environment. It is useful when the purpose of fork(2) would have been to create a new system context for an execve. Vfork() differs from fork in that the child borrows the parent's memory and thread of control until a call to execve(2) or an exit (either by a call to exit(2) or abnormally.) The parent process is suspended while the child is using its resources. Vfork() returns 0 in the child's context and (later) the pid of the child in the parent's context. Vfork() can normally be used just like fork. It does not work, however, to return while running in the childs context from the procedure that called vfork() since the eventual return from vfork() would then return to a no longer existent stack frame. Be careful, also, to call _exit rather than exit if you can't execve, since exit will flush and close standard I/O channels, and thereby mess up the parent processes standard I/O data structures. (Even with fork it is wrong to call exit since buffered data would then be flushed twice.) SEE ALSO
fork(2), execve(2), sigaction(2), wait(2), DIAGNOSTICS
Same as for fork. BUGS
This system call will be eliminated when proper system sharing mechanisms are implemented. Users should not depend on the memory sharing semantics of vfork as it will, in that case, be made synonymous to fork. To avoid a possible deadlock situation, processes that are children in the middle of a vfork() are never sent SIGTTOU or SIGTTIN signals; rather, output or ioctl(2) calls are allowed and input attempts result in an end-of-file indication. HISTORY
The vfork() function call appeared in 3.0BSD. 4th Berkeley Distribution June 4, 1993 4th Berkeley Distribution
All times are GMT -4. The time now is 12:31 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy