Linux cli command proc_pid_root

➡ A Linux man page (short for manual page) is a form of software documentation found on Linux and Unix-like operating systems. This man-page explains the command proc_pid_root and provides detailed information about the command proc_pid_root, system calls, library functions, and other aspects of the system, including usage, options, and examples of _. You can access this man page by typing man followed by the proc_pid_root.

  2 minute read  

NAME 🖥️ proc_pid_root 🖥️

symbolic link to root directory

DESCRIPTION

/proc/pid/root/
UNIX and Linux support the idea of a per-process root of the filesystem, set by the chroot(2) system call. This file is a symbolic link that points to the process’s root directory, and behaves in the same way as exe, and fd/*.

Note however that this file is not merely a symbolic link. It provides the same view of the filesystem (including namespaces and the set of per-process mounts) as the process itself. An example illustrates this point. In one terminal, we start a shell in new user and mount namespaces, and in that shell we create some new mounts:

$ PS1='sh1# ' unshare -Urnm
sh1# mount -t tmpfs tmpfs /etc  # Mount empty tmpfs at /etc
sh1# mount --bind /usr /dev     # Mount /usr at /dev
sh1# echo $$
27123

In a second terminal window, in the initial mount namespace, we look at the contents of the corresponding mounts in the initial and new namespaces:

$ PS1='sh2# ' sudo sh
sh2# ls /etc | wc -l                  # In initial NS
309
sh2# ls /proc/27123/root/etc | wc -l  # /etc in other NS
0                                     # The empty tmpfs dir
sh2# ls /dev | wc -l                  # In initial NS
205
sh2# ls /proc/27123/root/dev | wc -l  # /dev in other NS
11                                    # Actually bind
                                      # mounted to /usr
sh2# ls /usr | wc -l                  # /usr in initial NS
11

In a multithreaded process, the contents of the /proc/pid/root symbolic link are not available if the main thread has already terminated (typically by calling pthread_exit(3)).

Permission to dereference or read (readlink(2)) this symbolic link is governed by a ptrace access mode PTRACE_MODE_READ_FSCREDS check; see ptrace(2).

SEE ALSO

proc(5)

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

  █║▌│║█║▌★ KALI ★ PARROT ★ DEBIAN 🔴 PENTESTING ★ HACKING ★ █║▌│║█║▌

              ██╗ ██╗ ██████╗  ██████╗ ██╗  ██╗███████╗██████╗
             ████████╗██╔══██╗██╔═══██╗╚██╗██╔╝██╔════╝██╔══██╗
             ╚██╔═██╔╝██║  ██║██║   ██║ ╚███╔╝ █████╗  ██║  ██║
             ████████╗██║  ██║██║   ██║ ██╔██╗ ██╔══╝  ██║  ██║
             ╚██╔═██╔╝██████╔╝╚██████╔╝██╔╝ ██╗███████╗██████╔╝
              ╚═╝ ╚═╝ ╚═════╝  ╚═════╝ ╚═╝  ╚═╝╚══════╝╚═════╝

               █║▌│║█║▌ WITH COMMANDLINE-KUNGFU POWER █║▌│║█║▌

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░