This is weird, so I'm hoping someone here knows solaris and how it handles pipes...
OK... here goes...
Theres this log file, right? I want to tail -f it, grep that, gzip that, then pipe that into more commands. Well thats easy, right?
tail -f file | grep pattern | gzip | otherstuff...
... (1 Reply)
Hi,
Can the cd command be invoked using pipes???
My actual question is slightly different. I am trying to run an executable from different folders and the path of these folders are obtained dynamically from the front end. Is there a way in which i can actually run the executable... (2 Replies)
I am trying to figure out why when i have the following code
int main( { printf("0\n"); fork(); printf("1\n"); exit(0);}
and type in the shell
a.out | cat
the output of this program is
0
1
0
1
instead of
0
1
1
does anyone know? (3 Replies)
This is something I've given a lot of thought to and come up with no answer.
Say you have a data stream passing from a file, through process A, into process B. Process A only modifies a few bytes of the stream, then prints the rest of the stream unmodified. Is there any way to stream the file... (4 Replies)
Hi,
thanks for b4. can anyone tell me why following not working:
noUsers=$(who | cut -d" " -f1 | wc -l)
What i'm trying to do is get a list of logged on users and pass it to 'wc -l' and store the output to a variable. Any ideas? (1 Reply)
Hello all, I am trying to learn more about programming Unix pipes in C.
I have created a pipe that does od -bc < myfile | head
Now, I am trying to create od -bc < myfile | head | wc
Here is my code, and I know I might be off, thats why I am here so I can get some clarification.
#include... (1 Reply)
ls --color=always -laX | awk '{print $1, $3, $4, $2, $8}'
|sort -k 1,1 -k 9,9r
they work separately... but i don't know how to combine this to work.
thx! (1 Reply)
Hi, I have two programs, one is named "Master" and the other one "slave". What I want to do is , when I execute Master, inside slave will be called by excecl, do some calculations, and send those to the master program... A little example of what I am failing to do:
if ((PID1=fork())==0) { //... (6 Replies)
Discussion started by: lamachejo
6 Replies
LEARN ABOUT BSD
vfork
VFORK(2) System Calls Manual VFORK(2)NAME
vfork - spawn new process in a virtual memory efficient way
SYNOPSIS
pid = vfork()
int pid;
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), sigvec(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 ioctls are allowed and input attempts result in an end-of-file indication.
4th Berkeley Distribution June 30, 1985 VFORK(2)