I am implementing a shell. When attempting a command other than changing directories, execvp() runs, the child terminates and a new child is created. When I change directories, the child does not terminate and a new child is created. Here is a sample of my code: cd ../; ls; runs correctly, except I have to Ctrl+D twice to end the
Tag: fork
Using Fork for Command Line Arguements
I’m trying to execute the command “ls -l” but I’m not exactly sure how to approach it. This is what I’ve tried: However, the command doesn’t seem to work here. It works if I just simply use “ls” but I want to use “ls -l” is there another argument I have to pass to get this to work? Answer First
Fork process: Resume parent process while children terminated (Linux)
I’ve written a C++ application that waits until an event occurs (e.g. wait for incoming connection). After that event occured, it will continue by forking a child process that handles that event. So, my code looks essentially like this: My expectation now was that the child process will terminate (because of exit(0) and/or return). Indeed, it leaves the while loop,
How is the code segment shared between processes in Linux?
I have read about the copy-on-write principle which occurs when a new process is being forked in Linux. I have also read about the fact that if multiple instances of one program are running at the same time, only one instance of the program code can be found in the memory. I was wondering whether this is a direct consequence
Child process starts after parent process
I have a simple code to test the fork() function. It didn’t work as I expected. My expectation is: parent’s result and child’s result appear alternately. Can someone explain this and teach me how to fix it? Thanks! Answer The explanation is simple. Scheduling of processes is up to the kernel. If this is a single core processor then in
How fork() function works in this program?
I’m having some trouble with this program. I know what a fork() function does. It is used to create a new process from an existing process. The new process is called the child process, and the existing process is called the parent. The parent returnes the child’s pid and the child returns 0. That said, I find hard to understand
Linux-C: reading from pipe returns first buffer written to it
This program simulates a variant of Dijkstra’s Producer/Consumer problem. A pipeline is first created followed by a child process using fork(). The child will then write to the pipe a crudely done randomly generated piece of “stock market ticker information”. After waiting for the child/producer process to write this information, the parent/consumer process will read it out. The first output
Interpreting STRACE output – pipes and forks
I have the following code written in C, taken from https://beej.us/guide/bgipc/html/multi/pipes.html: When compiling and running this code in the terminal using strace I get the following output: Can anybody explain, line by line, what is going on in the strace output? I’ve attempted to research how to interpret strace outputs but haven’t had any luck. Thanks in advance. Answer The
How does the fork() know whether it is in child process and in parent process? [closed]
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 9 years ago. Improve this question When a fork() system call gets executed , the processor turns into kernel mode. Thus at the end of the
Counter increase in child & parent with fork()
I’ve a problem with this little program: I increase the counter in the child but in the parent the counter not increase… why? Thank you everyone Answer That’s because after fork, parent process and child process are different processes, and they each have their own copy of the variable count.