10-29-2008
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1. UNIX for Dummies Questions & Answers
Hi
I have a script, where i need to execute the follwoing scripts/commands in my script. but those should be executed one by one
cd /aa/205/jams
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2. Shell Programming and Scripting
Did not use 'wait' yet.
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3. Shell Programming and Scripting
Hi All,
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4. Red Hat
hi all,
We are trying to run a process in the background and in the process we call fork ;and wait for the child process to finish .We find that the died = wait(&status); happens after 10 seconds randomly and sometimes completes in time (within 1 sec)
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5. Red Hat
hi all,
We are trying to run a process in the background and in the process we call fork ;and wait for the child process to finish .We find that the died = wait(&status); happens after 10 seconds randomly and sometimes completes in time (within 1 sec)
This behavior is seen only when the... (1 Reply)
Discussion started by: vishnu.priya
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6. Programming
Hello everybody.I want to make clear that i am not going to ask from anybody to build my asignement but i have a big problem. I can't seem to find anywhere ONE good example on C about what i am trying to do:wall:.I think it is simple. All i ask is one example, even a link is fine.
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7. Programming
Hi All,
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8. Shell Programming and Scripting
Hi,
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9. BSD
Hi Experts,
I am facing one problem here which is one process always stuck in running state which causes the other similar process to sleep state . This causes my system in hanged state.
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10. UNIX for Advanced & Expert Users
Hi Experts,
I am facing one problem here which is one process always stuck in running state which causes the other similar process to sleep state . This causes my system in hanged state.
On doing cat /proc/<pid>wchan showing the "__init_begin" in the output.
Can you please help me here... (1 Reply)
Discussion started by: naveeng
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VFORK(2) BSD System Calls Manual VFORK(2)
NAME
vfork -- spawn new process in a virtual memory efficient way
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
pid_t
vfork(void);
DESCRIPTION
The vfork system call creates a new process that does not have a new virtual address space, but rather shares address space with the parent,
thus avoiding potentially expensive copy-on-write operations normally associated with creating a new process. It is useful when the purpose
of fork(2) would have been to create a new system context for an execve(2). The vfork system call differs from fork(2) 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.
The vfork system call returns 0 in the child's context and (later) the pid of the child in the parent's context.
The vfork system call can normally be used just like fork(2). 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(2) rather than exit(3) if you can't execve(2), since exit(3) will flush and close standard I/O channels, and thereby mess
up the standard I/O data structures in the parent process. (Even with fork(2) it is wrong to call exit(3) since buffered data would then be
flushed twice.)
RETURN VALUES
Same as for fork(2).
ERRORS
Same as for fork(2).
SEE ALSO
execve(2), fork(2), sigaction(2), wait(2)
HISTORY
The vfork() function call appeared in 3.0BSD. In 4.4BSD, the semantics were changed to only suspend the parent. The original semantics were
reintroduced in NetBSD 1.4.
BUGS
Users should not depend on the memory sharing semantics of vfork() as other ways of speeding up the fork process may be developed in the
future.
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.
BSD
January 3, 1998 BSD