#include<unistd.h>
#include<fcntl.h>
int main()
{
close(STDOUT_FILENO);
close(STDERR_FILENO);
if((write(STDIN_FILENO,"arrgh!",6))==-1)
{
perror("error writing to file");
}
}
i get no output or error whatsoever
but when i perform the same exercise on my original code
i get
Code:
[c_d@localhost C scratchpad]$ ./a.out <file
error writing to file: Bad file descriptor
[c_d@localhost C scratchpad]$ echo watup | ./a.out
error writing to file: Bad file descriptor
Quote:
In this case, the shell opened /dev/tty for reading and writing and made all three initial fd's point to it.
i wanted to see that...but i m not able to make fcntl() work...
Code:
#include<unistd.h>
#include<fcntl.h>
#include<stdlib.h>
int main()
{
int x=2,file,fd;
if((file=open("fdvals",O_RDWR))==-1)
{
perror("error opening fdvals");
}
fd=fcntl(file,F_GETFD,0);
printf("fd=%d",fd);
fd=fcntl(STDOUT_FILENO,F_GETFD,0);
printf("fd=%d",fd);
}
I 'm using RH 7.2 Genome in the Network Configuration I change therer are two places one for static hostname for my machine and in DNS hostname I don't know what happen when restarting my PC when connecting using dialer I can't browse the Internet also I can't use sendmail .......Server timeout... (2 Replies)
The #1 Online Store for Louis Vuitton Replicas is: http://www.opichina.com.cn.
We offer Louis Vuitton Replicas and more! Whatever you call it: LV Bags, LV Replicas, Louis Vuitton Fake, Louis Vuitton Knockoffs, Louis Vuitton Bag, Louis Vuitton Purse, Louis Vuitton Wallet, Louis Vuitton Shoes,... (10 Replies)
Hi,
Could someone please tell me what would happen if the following were entered into the command line:
rm -i /books/*.*
rm /books/*
Many thanks! (3 Replies)
I have an unix id (AIX system) which is used to run a couple of processes. They also write some log files into a file system (that is not in the home directory of the user id, but in different location).
One bad day, the id was deleted accidentally. But the home directory, files and everything... (1 Reply)
I'm talking about boot process in multi-boot Linux perceptive.
Please tell me whether my explanation is right or wrong? If wrong, please explain.
"The BIOS checks the system and loads this initial bootstrapping code into
memory. This initial bootstrap code searches for an active partition... (0 Replies)
Hello,
Who actually wrote Professional Linux Programming of Wrox publication as there are two different sets of writers, one set consists of Jon Masters and Richard Blum and another set of writers is Neil Mathew with lots of other writers. Plz resolve it. I'm really confused.
Regards.. (0 Replies)
Hi everyone. Silly might be silly be I'm still new to bash. I'm trying to make an Alarm Clock for in the morning using my laptop i have wrote this Simple Script but i cant work out how to play it at a certain time.
#!/bin/bash
cd /home/josh/Music/Bruno_Mars/Hooligans/
cvlc... (8 Replies)
Well I wrote this in 2005 and uploaded to AMINET.as a commemoration of a machine that is still in use today.
It is now 29 years since this machne came into being. Phenominal and it is still being supported- WOW!
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... (0 Replies)
Discussion started by: wisecracker
0 Replies
LEARN ABOUT OPENDARWIN
mount_fdesc
MOUNT_FDESC(8) BSD System Manager's Manual MOUNT_FDESC(8)NAME
mount_fdesc -- mount the file-descriptor file system
SYNOPSIS
mount_fdesc [-o options] fdesc mount_point
DESCRIPTION
The mount_fdesc command attaches an instance of the per-process file descriptor namespace to the global filesystem namespace. The conven-
tional mount point is /dev and the filesystem should be union mounted in order to augment, rather than replace, the existing entries in /dev.
This command is normally executed by mount(8) at boot time.
The options are as follows:
-o Options are specified with a -o flag followed by a comma separated string of options. See the mount(8) man page for possible options
and their meanings.
The contents of the mount point are fd, stderr, stdin, stdout and tty.
fd is a directory whose contents appear as a list of numbered files which correspond to the open files of the process reading the directory.
The files /dev/fd/0 through /dev/fd/# refer to file descriptors which can be accessed through the file system. If the file descriptor is
open and the mode the file is being opened with is a subset of the mode of the existing descriptor, the call:
fd = open("/dev/fd/0", mode);
and the call:
fd = fcntl(0, F_DUPFD, 0);
are equivalent.
The files /dev/stdin, /dev/stdout and /dev/stderr appear as symlinks to the relevant entry in the /dev/fd sub-directory. Opening them is
equivalent to the following calls:
fd = fcntl(STDIN_FILENO, F_DUPFD, 0);
fd = fcntl(STDOUT_FILENO, F_DUPFD, 0);
fd = fcntl(STDERR_FILENO, F_DUPFD, 0);
Flags to the open(2) call other than O_RDONLY, O_WRONLY and O_RDWR are ignored.
The /dev/tty entry is an indirect reference to the current process's controlling terminal. It appears as a named pipe (FIFO) but behaves in
exactly the same way as the real controlling terminal device.
FILES
/dev/fd/#
/dev/stdin
/dev/stdout
/dev/stderr
/dev/tty
SEE ALSO mount(2), unmount(2), tty(4), fstab(5), mount(8)CAVEATS
No ~. and .. entries appear when listing the contents of the /dev/fd directory. This makes sense in the context of this filesystem, but is
inconsistent with usual filesystem conventions. However, it is still possible to refer to both ~. and .. in a pathname.
This filesystem may not be NFS-exported.
HISTORY
The mount_fdesc utility first appeared in 4.4BSD.
4.4BSD March 27, 1994 4.4BSD