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1
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1answer
3k views

Apache cannot fork: cannot allocate memory

I am running apache on Fedora with mod_perl. The server forks a process to send an email frequently - and the fork exits. Suddenly, I got: Cannot fork: Cannot allocate memory. There was plenty of ...
33
votes
2answers
3k views

Why is the default process creation mechanism fork?

The UNIX system call for process creation, fork(), creates a child process by copying the parent process. My understanding is that this is almost always followed by a call to exec() to replace the ...
6
votes
4answers
11k views

How to totally fork a shell command that is using redirection

I've written quite a few shell scripts over the years (but I'm certainly not a sysadmin) and there's something that always caused me troubles: how can I fork a shell command immune to hangups in the ...
5
votes
1answer
240 views

Why is the following command killing a system?

Anyone understand the following code , running in bash ? :(){ :|:& };: It seems to be a "fork" bomb on Linux.
2
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1answer
581 views

There is no bash indicator prompt after a forked process terminates

I am reading the book Advanced Programming in the Unix Environment. There is a test program to test the fork function. It works well in my Ubuntu. But what I confused is that why there is no command ...
2
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3answers
2k views

Fork: Negative return value

From the fork(2) man page: RETURN VALUE On success, the PID of the child process is returned in the parent, and 0 is returned in the child. On failure, -1 is returned in the parent, no ...
8
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3answers
2k views

Process descendants

I'm trying to build a process container. The container will trigger other programs. For example - a bash script that launches running background tasks with '&' usage. The important feature I'm ...
9
votes
3answers
12k views

Does bash support forking similar to C's fork()?

I have a script that I would like to fork at one point so two copies of the same script are running. For example, I would like the following bash script to exist: echo $$ do_fork() echo $$ If this ...
9
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4answers
3k views

Why should a child of a vfork or fork call _exit() instead of exit()?

From the man page of vfork(): vfork() differs from fork() in that the parent is suspended until the child makes a call to execve(2) or _exit(2). The child shares all memory with its ...
10
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1answer
4k views

What's the difference between fork() and vfork()?

I would like to understand in detail the difference between fork() and vfork(). I was not able to digest the man page completely. I would also like to clarify one of my colleagues comment "In ...
15
votes
4answers
7k views

After fork(), where does the child begin its execution?

I'm trying to learn UNIX programming and came across a question regarding fork(). I understand that fork() creates an identical process of the currently running process, but where does it start? For ...