I need to disable file access (fopen, freopen, open etc) for application which is running under chroot jail and with restrictions (rlimit) via execv. Before that I redirected stdin/out to files within jail. I tried this:
Code:
// Redirect stdin/stdout to files
int fd = open (file_input, O_RDONLY);
if (fd < 0)
fatal_error ("input open failed!");
[Code].....
Consider the following code:
Code:
int main()
{
int i=0;
pid_t pid;
for(i=0;i<2;i++)
[code]....
I get the following output:
Parent: chid_pid=4356 i=0 parent's pid=4355
This is child 4356 i=0
This is child 4357 i=1
[code]....
I can observe instead of two children(as I expect) processes there are three. This is because child process 4356 creates its own child. Why all the messages of the type "This is child X i=Y" are concentrated one under another? How exactly fork works? Is affected by the fact that I have a dual-core processor?
I have a doubt about signals in C programming. I have done this little program to explain it. It creates a child process with fork and, when the child ends, receives the SIGCHLD signal and wait for its termination.Ok, quite easy, BUT when I execute this code the SIGCHLD signal is received twice, first as an error (returns -1) and the second one to finish the child process.I don't understand the meaning of the first received signal. Why is it generated? Is the code wrong? (if you add the SIGINT and press Ctrl+C during the execution it also receives two signals instead of one)
Code: #include <stdio.h>
#include <unistd.h>
#include <string.h>
[code]....
I have a root process (on linux) that forks a child and the child process then drops privileges by doing a setuid() to a normal user. After the child setuid()'s, it is of course impossible for it to gain root again by itself. But since the main process is still running as root, i was wondering if there was a simple/smart way of getting the root-master-process to elevate the child back to root (or maybe just to another non-privi uid). Is there some way to do a setuid() on another pid? or maybe something can be done through /proc/<pid>/? Killing the child is not an option (because its what it does today and im trying to find a smarter way). (The program is apache2's mpm-itk worker and the "child" is the actual apache2 process serving a page.)
View 11 Replies View RelatedIm using gdb for debugging my application.. I was able to debug child process(when fork comes) .. and in child process we have an exec call to .... So the problem is, when the control come to exec , the exec process is executing at a time... I could not debug the exec. process... error is stack curruption due to same frame So, is there any way to debug the exec process
View 1 Replies View RelatedI'm writing a sort of toy shell using fork() and execv(). It runs smoothly enough untill the user enters an invalid command at which point the program hangs, so I need a way to check if the program loaded using execv returned correclty or not in the parent process and kill it if it didntI tried writing stderr to a text file to see if something whent wrong but doesnt really work out. Try running ./digenv GDM -i -Q for instance. (-Q is an invalid option for grep which the program runs at a certain point).Heres the code:
Code:
//digenv
//Carl Reg�rdh 2011-03-24
[code]....
I'm trying to write a shell script that do ftp and download file periodically, this script should be called by a daemon running in the background.
the shell script "script.sh" is as follows:
Code:
yafc ftp://test:test@192.168.1.225:21 < commands
and the "commands" files is
Code:
d Root/md5* /
quit
if I run script.sh it will work just fine. But when the daemon software calls the "script.sh", the script will send ftp login request to the ftp server, but will not even answer the username or anything.
I believe it is something about child process redirection, but I don't know how to deal with it.
This problem is not only with yafc, it is the same with any ftp client or any application like telnet and so.
what I am trying to do is to pass an argument to the standard input stream of a child process. I mean I create two programs .. first one invokes the other. second one contains something like
Code:
scanf("%d", &n);
now I want my first program to be able to pass a value to the second one so that it gets stored in n.
I want to kill parent process after "fork()" method. but if I kill parent process with "exit(0)" method, main() thread is terminated as well so child prosess doesn't work anymore. Is there any way to kill only parent process without affecting to child process?
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
[code]....
i got basic knowledge about creating a single child from a parent using fork(). But when it comes into creating multiple children, i am simply stuck. I am trying to create two processes from a parent and it would wait for both two processes to finish. my attempt is as below
[Code]....
I am developing a application. In this I fork() 3 childs(lets say child1 , child2, child3) . The parent is now waiting for some input from keyboard.Child3 is continously getting data from child1 and child2 using pipe which it then will print using printf.Now as the parent is waiting for input from user through keyboard while child3 is continously printing the data. I want to do it in different terminals.Can you please guide me how to proceed ahead so that on one terminal , the parent waits for input fromser while on other terminal child3 prints data.
View 1 Replies View RelatedI am going to create a parent process and fork a child process from it. I want to write a code in such a way that whenever my child process end it must indicate that the child process is terminated by a signal or not. This code must be written in the parent process block.
View 6 Replies View RelatedI am troubleshooting something and I got this problem.
If I do "pstree -p"
It shows,
Code:
[code]....
However, it does NOT show up in "ps -elf"
Code:
ps -elf | grep soffi
0 S whho 7734 1 0 80 0 - 36435 - 11:14 pts/2 00:00:03 /usr/lib/openoffice/program/soffice.bin -splash-pipe=5
0 S whho 7833 7759 0 80 0 - 751 - 11:21 pts/3 00:00:00 grep soffi
I was wondering if 7735, 7736, 7737, 7743 were really processes. Then I checked /proc, I could cd to /proc/7735, /proc/7736, etc, but I could not ls them out. I looked at the man page of "pstree", it says,
Code:
Child threads of a process are found under the parent process and are shown with the process name in curly braces, e.g.
icecast2---13*[{icecast2}]
So, what does all this mean? Does it mean that 7735, 7736, 7737, 7743 are just threads but not processes? If so, why could I cd to /proc/<id> but not see them in "ps -elf".
Code:
int main()
{
int pi;
int i=10;
pid=fork();
[code]....
Q 1. The value of the variable pid returned by the fork() function will be greater than 0 in the parent process and equal to zero in the child process? but during forking, there values are exactly copied so what's went wrong here?
Q 2. "changes to the variable in one process is not reflected in the other process" why it is so? >> Even if we have variable i declared as a pointer or a global it wont make a difference.
Code:
int main()
{
int i, pid;
i=10;
printf("before fork i is %d
[code]....
Q. Through this program it is clear that both process is using the data from the same location, so where's the original value is residing when the child process is in execution.?
What i am trying to do is i want to add numbers from 1 to 100. but that too using multiprocessing. So i made a c programme and using fork() command made two child processes. Now in one child process i am adding from 1 to 50. and in another i am adding 51 to 100. and then in the parent process adding the two results to get the final one. Now the result from the two function i am getting correctly. But after the wait() call the value returned is lost : See the programme below for reference
# include<stdio.h>
# include<unistd.h>
# include<sys/wait.h>
# include<stdlib.h>
[code].....
I just installed Maya 2009 on Fedora 13.It seemed to run the RPM install fine, but when I go to Applications > Graphics > MayaI an error:Could not launch 'Autodesk Maya 2009 (64-bit)
Failed to execute child process "/usr/autodesk/aya/bin/maya"(no such file or directory)I browsed to this location in the file browser and there definately is a file called maya in "bin"
There seems to be a common solution to get the webcam working with Skype - rather than launching with Skype you launch with LD_PRELOAD=/usr/lib32/libv4l/v4l2convert.so skype - so far so good. When I do this I get the error There was an error launching the application. Details: Failed to execute child process "LD_PRELOAD=/usr/lib32/libv4l/v4l2convert.so" (No such file or directory). But I do have that directory and file on my system.
A ubuntu community doc talks about the terminal command sudo ld.so.preload-manager when I action this I get sudo ld.so.preload-manager /usr/lib/libv4l/v4l1compat.so [sudo] password for dad: sudo: ld.so.preload-manager: command not found
I have ubuntu 10.04.1 and a H.P.psc 1311 all-in-one printer scanner.Printer works ok but when trying to scan,with xsane,it goes through the scanning process and an image of the document comes up on the screen.
When I try to save this image to desktop or file/folder whatever I get the message; "Child Process Error. Failed to execute OCR command:GOCR:no such file or directory."
Code:
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
[code]....
Description of what the code does or what i intended to do:
1. Created a child process from parent process using 'fork()'
2. Sent a signal 'SIGALRM' from child process to parent process using 'sigqueue' function.
(The Third parameter of 'siqueue' function contains the message (message msg) which the child process wants to send to the parent process.'msg' is a stucture instance containing a) pid of child and b) string) 5. Print the 'msg' sent by child process inside the signal handler function 'sig_action_function' of the parent process I am getting some junk value when this line is executed
Code:
printf("%d
",msg->cpid);
I expected to get the pid of child process, which the child process sent to parent process through the signal.
Failed to execute child process "gnome-help" (No such file or directory)I get this error when clicking on the Help button in, for example, the preferences dialog box like for the Time and Date panel.I cannot find anything in the Synaptic Pkg. Mgr. or Ubuntu Software Center that indicates "gnome-help".
View 3 Replies View RelatedI've installed MatLab in my Acer Aspire one netbook which runs karmic. Does anyone know what can cause this error message from appearing when i click on the icon? Could not launch 'MATLAB R2009a' Failed to execute child process "matlab" (No such file or directory)
View 1 Replies View RelatedWhat can I do about this?
Failed to execute child process "realplay" (No such file or directory)
using gdome Ubuntu, realplayer is in my Home folder (RealPlayer11GOLD)
When I press )print screen button ) it says ....here was an error running gnome-screenshot:Failed to execute child process "gnome-screenshot" (No such file or directory)
View 4 Replies View RelatedI have a problem, I need to launch another binary from my application, but I need to get the control back once the other binary is initialized. fork/exec doesn't seem to give anything on that side using pthreads I'm able to wait until the new thread exits, but that's not what I want at the moment I'm using popen, but it doesn't seem to do the job right...
View 14 Replies View RelatedI haven't programmed in C for a while, so I am trying to remember certain aspects of syntax. I have a program that will fork and exec other programs. Those programs will be specified on the command line as follows:
./main "prog1 arg arg ..." "prog2 arg arg ..."
Here is the main snippet:
int countChar(char* s, char c)
{ int cnt = 0;
int len = strlen(s);
for(int i = 0; i < len; i++)
[code]....
The highlighted line is the problem. I get this error:
dualstarter.cpp:58: error: initializer fails to determine size of 'params'.
Right now I am thinking of creating an array with the specified size and simply copying the required string into it, but it just seems like there is an easier way.
Brand new to Linux. Sort of got thrown in front of the bus if you know what I mean. The company I work for has a Linux server running CentOS 5.4 Company uses Linux for their Email, FTP and Web Server. Have been here a few years dabbling in and out of Linux and now that the old Admin has left the company.....I need to learn it ASAP. The server has run pretty solid until today.
The email server runs SendMail and SpamAssasin. Received lots of complaints today regarding extra SPAM. Noticed that SpamAssassin was not running. Tried to restart it through the WebMin tools and got the following error: Starting spamd: child process [3956] exited or timed out without signaling production of a PID file: exit 255 at /usr/bin/spamd line 2588.
I'm using Ubuntu x64 (dunno which version, but I don't think it matters) and I'm concerned about security with PHP.I remember using lighttpd and I had some mystic configuration and the secuirty was perfect for me - if one website gets hacked then the others are still safe (kinda).Now with apache2 if I enable safemode I'm still able to go outside web directory and actually I can go really far untill user/group matches.I tested the system with r57shell and I was able to mess up other websites.Is there a way to disallow access to other websites?
View 5 Replies View RelatedI have Windows 7 and Ubuntu 10.04 installed on the same harddrive. I'm using grub to boot both. I would like to deny access to the windows partitions, but allow access to removable drives and shared drives.
View 2 Replies View Relatedwhat is child process - GE cannot open
View 1 Replies View RelatedWhat happens to a child process that dies and has no parent process to wait for it and what's bad about this?
View 2 Replies View Related