I tried using the following code to execute a program but it doesnt seems to be working .. I would like to know whats wrong wit it .
execve("/bin/cat", "words", NULL); (0 Replies)
Hi,
Program A: uses pipe()
I am able to read the stdout of PROGAM B (stdout got through system() command) into PROGRAM A using:
* child
-> dup2(fd, STDOUT_FILENO);
-> execl("/path/PROGRAM B", "PROGRAM B", NULL);
* parent
-> char line;
-> read(fd, line, 100);
Question:... (2 Replies)
hello everybode.Got some sort of "problems" with this stuff;
well this is a program
int main()
{
int Pipe;
int origStdin, origStdout;
int childPID;
origStdin = dup(0);
origStdout = dup(1);
pipe(Pipe);
if( (childPID = fork()) < 0 )
{
perror(... (2 Replies)
Hi,
I'm writing a monitor program that can be notified once a process makes an execve system call and then stop that process for examining before it starts to run the new code. I know I can ptrace a process to achieve this, but I do not want to ptrace every process in the system. Is it possible?... (1 Reply)
Disclaimer: This is just a rainy day experiment. There is no expected "goal" other than to understand UNIX better.
After reading about fork and exec, my understanding is that forking, as the UNIX shell does by design, consequentially may sacrafice some speed versus an approach that runs in... (1 Reply)
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.
So, i want to... (1 Reply)
Hi guys,
I need to know how i can ignore Pipe '|' if Pipe is coming as a column in Pipe delimited file
for eg:
file 1:
xx|yy|"xyz|zzz"|zzz|12...
using below awk command
awk 'BEGIN {FS=OFS="|" } print $3
i would get xyz
But i want as :
xyz|zzz to consider as whole column... (13 Replies)
Hi,
I have the following scenario..
1) I have a binary which i launch from command line. It executes fine.
2) But when I launch it from another file using execve command, it gives a message that it is not able to access a shared object ".so" in /usr/bin (message is "Permission... (4 Replies)
The task I have to do is something along the lines "I receive some input and based on the first character I send it through pipe to one of the children to print".
The scheme it is based on is 1->2; 1->3; 1->4; 2 will print all the input that starts with a letter, 3 will print all the input that... (2 Replies)
Discussion started by: Ildiko
2 Replies
LEARN ABOUT OSX
close
CLOSE(2) BSD System Calls Manual CLOSE(2)NAME
close -- delete a descriptor
SYNOPSIS
#include <unistd.h>
int
close(int fildes);
DESCRIPTION
The close() call deletes a descriptor from the per-process object reference table. If this is the last reference to the underlying object,
the object will be deactivated. For example, on the last close of a file the current seek pointer associated with the file is lost; on the
last close of a socket(2) associated naming information and queued data are discarded; on the last close of a file holding an advisory lock
the lock is released (see further flock(2)).
When a process exits, all associated file descriptors are freed, but since there is a limit on active descriptors per processes, the close()
function call is useful when a large quantity of file descriptors are being handled.
When a process forks (see fork(2)), all descriptors for the new child process reference the same objects as they did in the parent before the
fork. If a new process is then to be run using execve(2), the process would normally inherit these descriptors. Most of the descriptors can
be rearranged with dup2(2) or deleted with close() before the execve is attempted, but if some of these descriptors will still be needed if
the execve fails, it is necessary to arrange for them to be closed if the execve succeeds. For this reason, the call ``fcntl(d, F_SETFD,
1)'' is provided, which arranges that a descriptor will be closed after a successful execve; the call ``fcntl(d, F_SETFD, 0)'' restores the
default, which is to not close the descriptor.
RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and the global integer variable errno is set to
indicate the error.
ERRORS
The close() system call will fail if:
[EBADF] fildes is not a valid, active file descriptor.
[EINTR] Its execution was interrupted by a signal.
[EIO] A previously-uncommitted write(2) encountered an input/output error.
SEE ALSO accept(2), execve(2), fcntl(2), flock(2), open(2), pipe(2), socket(2), socketpair(2)STANDARDS
Close() conforms to IEEE Std 1003.1-1988 (``POSIX.1'').
4th Berkeley Distribution April 19, 1994 4th Berkeley Distribution