clone2 - Linux
Overview
clone2 is an advanced Linux system call that creates a child process with specific process characteristics. It provides extended control over the child process’s resource allocation, thread creation, and file system namespace.
Syntax
clone2(flags, newsp, tidptr, child_stack, stack_size)
Options/Flags
- flags: A bitmask of flags that specify the process characteristics of the child process. Commonly used flags include:
- CLONE_NEWNS: Create a new network namespace
- CLONE_NEWUTS: Create a new hostname and sysname namespace
- CLONE_NEWIPC: Create a new IPC namespace
- CLONE_NEWUSER: Create a new user namespace
- newsp: Pointer to a new namespace
- tidptr: Pointer to a variable that will hold the TID (thread ID) of the child process
- child_stack: Pointer to the stack of the child process
- stack_size: Size of the stack for the child process
Examples
Create a child process in a new network namespace:
clone2(CLONE_NEWNS, 0, NULL, NULL, 0);
Create a child process with a different hostname:
clone2(CLONE_NEWUTS, 0, NULL, NULL, 0);
set hostname("new-hostname");
Common Issues
- Permission denied: The user may not have sufficient privileges to create a new namespace.
- Invalid argument: Check that the flags and namespace arguments are valid.
- Stack overflow: Ensure that the specified stack size is sufficient for the child process.
Integration
clone2 can be combined with other commands to perform advanced tasks:
- unshare: Create a new namespace for the current process using unshare and clone2 to create child processes within the new namespace.
- chroot: Change the root directory of the child process to a different file system within a new namespace.
- forkpty: Create a child process with a pseudo-terminal attached for interactive use.
Related Commands
- fork(2)
- vfork(2)
- execve(2)
- namespaces(7)