обзор иерархии файловой системы (File system hierarchy overview)
VIRTUAL KERNEL AND API FILE SYSTEMS
/dev/
The root directory for device nodes. Usually, this directory
is mounted as a "devtmpfs" instance, but might be of a
different type in sandboxed/containerized setups. This
directory is managed jointly by the kernel and
systemd-udevd(8), and should not be written to by other
components. A number of special purpose virtual file systems
might be mounted below this directory.
/dev/shm/
Place for POSIX shared memory segments, as created via
shm_open(3). This directory is flushed on boot, and is a
"tmpfs" file system. Since all users have write access to
this directory, special care should be taken to avoid name
clashes and vulnerabilities. For normal users, shared memory
segments in this directory are usually deleted when the user
logs out. Usually, it is a better idea to use memory mapped
files in /run/ (for system programs) or $XDG_RUNTIME_DIR (for
user programs) instead of POSIX shared memory segments, since
these directories are not world-writable and hence not
vulnerable to security-sensitive name clashes.
/proc/
A virtual kernel file system exposing the process list and
other functionality. This file system is mostly an API to
interface with the kernel and not a place where normal files
may be stored. For details, see proc(5). A number of special
purpose virtual file systems might be mounted below this
directory.
/proc/sys/
A hierarchy below /proc/ that exposes a number of kernel
tunables. The primary way to configure the settings in this
API file tree is via sysctl.d(5) files. In
sandboxed/containerized setups, this directory is generally
mounted read-only.
/sys/
A virtual kernel file system exposing discovered devices and
other functionality. This file system is mostly an API to
interface with the kernel and not a place where normal files
may be stored. In sandboxed/containerized setups, this
directory is generally mounted read-only. A number of special
purpose virtual file systems might be mounted below this
directory.
