NAME<\/a> file-hierarchy \u2212 File system hierarchy overview<\/p>\n Operating systems using the systemd<\/b>(1) system and service manager are organized based on a file system hierarchy inspired by UNIX, more specifically the hierarchy described in the File System Hierarchy<\/font><\/b> [1]<\/font><\/small> specification and hier<\/b>(7), with various extensions, partially documented in the<\/font> XDG Base Directory Specification<\/font><\/b> [2]<\/font><\/small> and<\/font> XDG User Directories<\/font><\/b> [3]<\/font><\/small> . This manual page describes a more generalized, though minimal and modernized subset of these specifications that defines more strictly the suggestions and restrictions systemd makes on the file system hierarchy.<\/font><\/p>\n Many of the paths described here can be queried with the systemd-path<\/b>(1) tool.<\/font><\/p>\n \/<\/font><\/p>\n The file system root. Usually writable, but this is not required. Possibly a temporary file system (“tmpfs”). Not shared with other hosts (unless read\u2212only).<\/font><\/p>\n \/boot\/<\/font><\/p>\n The boot partition used for bringing up the system. On EFI systems, this is possibly the EFI System Partition (ESP), also see systemd-gpt-auto-generator<\/b>(8). This directory is usually strictly local to the host, and should be considered read\u2212only, except when a new kernel or boot loader is installed. This directory only exists on systems that run on physical or emulated hardware that requires boot loaders.<\/font><\/p>\n \/efi\/<\/font><\/p>\n If the boot partition \/boot\/ is maintained separately from the EFI System Partition (ESP), the latter is mounted here. Tools that need to operate on the EFI system partition should look for it at this mount point first, and fall back to \/boot\/ \u2014 if the former doesn’t qualify (for example if it is not a mount point or does not have the correct file system type MSDOS_SUPER_MAGIC<\/b>).<\/font><\/p>\n \/etc\/<\/font><\/p>\n System\u2212specific configuration. This directory may or may not be read\u2212only. Frequently, this directory is pre\u2212populated with vendor\u2212supplied configuration files, but applications should not make assumptions about this directory being fully populated or populated at all, and should fall back to defaults if configuration is missing.<\/font><\/p>\n \/home\/<\/font><\/p>\n The location for normal user’s home directories. Possibly shared with other systems, and never read\u2212only. This directory should only be used for normal users, never for system users. This directory and possibly the directories contained within it might only become available or writable in late boot or even only after user authentication. This directory might be placed on limited\u2212functionality network file systems, hence applications should not assume the full set of file API is available on this directory. Applications should generally not reference this directory directly, but via the per\u2212user $HOME<\/i> environment variable, or via the home directory field of the user database.<\/font><\/p>\n \/root\/<\/font><\/p>\n The home directory of the root user. The root user’s home directory is located outside of \/home\/ in order to make sure the root user may log in even without \/home\/ being available and mounted.<\/font><\/p>\n \/srv\/<\/font><\/p>\n The place to store general server payload, managed by the administrator. No restrictions are made how this directory is organized internally. Generally writable, and possibly shared among systems. This directory might become available or writable only very late during boot.<\/font><\/p>\n \/tmp\/<\/font><\/p>\n The place for small temporary files. This directory is usually mounted as a “tmpfs” instance, and should hence not be used for larger files. (Use \/var\/tmp\/ for larger files.) Since the directory is accessible to other users of the system, it is essential that this directory is only written to with the mkstemp<\/b>(3), mkdtemp<\/b>(3) and related calls. This directory is usually flushed at boot\u2212up. Also, files that are not accessed within a certain time are usually automatically deleted. If applications find the environment variable $TMPDIR<\/i> set, they should prefer using the directory specified in it over directly referencing \/tmp\/ (see environ<\/b>(7) and<\/font> IEEE Std 1003.1<\/font><\/b> [4]<\/font><\/small> for details). For further details about this directory, see<\/font> Using \/tmp\/ And \/var\/tmp\/ Safely<\/font><\/b> [5]<\/font><\/small> .<\/font><\/p>\n \/run\/<\/font><\/p>\n A “tmpfs” file system for system packages to place runtime data in. This directory is flushed on boot, and generally writable for privileged programs only. Always writable.<\/font><\/p>\n \/run\/log\/<\/font><\/p>\n Runtime system logs. System components may place private logs in this directory. Always writable, even when \/var\/log\/ might not be accessible yet.<\/font><\/p>\n \/run\/user\/<\/font><\/p>\n Contains per\u2212user runtime directories, each usually individually mounted “tmpfs” instances. Always writable, flushed at each reboot and when the user logs out. User code should not reference this directory directly, but via the $XDG_RUNTIME_DIR<\/i> environment variable, as documented in the<\/font> XDG Base Directory Specification<\/font><\/b> [2]<\/font><\/small> .<\/font><\/p>\n \/usr\/<\/font><\/p>\n Vendor\u2212supplied operating system resources. Usually read\u2212only, but this is not required. Possibly shared between multiple hosts. This directory should not be modified by the administrator, except when installing or removing vendor\u2212supplied packages.<\/font><\/p>\n \/usr\/bin\/<\/font><\/p>\n Binaries and executables for user commands that shall appear in the $PATH<\/i> search path. It is recommended not to place binaries in this directory that are not useful for invocation from a shell (such as daemon binaries); these should be placed in a subdirectory of \/usr\/lib\/ instead.<\/font><\/p>\n \/usr\/include\/<\/font><\/p>\n C and C++ API header files of system libraries.<\/font><\/p>\n \/usr\/lib\/<\/font><\/p>\n Static, private vendor data that is compatible with all architectures (though not necessarily architecture\u2212independent). Note that this includes internal executables or other binaries that are not regularly invoked from a shell. Such binaries may be for any architecture supported by the system. Do not place public libraries in this directory, use $libdir<\/i> (see below), instead.<\/font><\/p>\n \/usr\/lib\/arch\u2212id<\/i>\/<\/font><\/p>\n Location for placing dynamic libraries into, also called $libdir<\/i>. The architecture identifier to use is defined on<\/font> Multiarch Architecture Specifiers (Tuples)<\/font><\/b> [6]<\/font><\/small> list. Legacy locations of $libdir<\/i> are \/usr\/lib\/, \/usr\/lib64\/. This directory should not be used for package\u2212specific data, unless this data is architecture\u2212dependent, too. To query $libdir<\/i> for the primary architecture of the system, invoke:<\/font><\/p>\n # systemd\u2212path system\u2212library\u2212arch<\/font><\/p>\n \/usr\/share\/<\/font><\/p>\n Resources shared between multiple packages, such as documentation, man pages, time zone information, fonts and other resources. Usually, the precise location and format of files stored below this directory is subject to specifications that ensure interoperability.<\/font><\/p>\n \/usr\/share\/doc\/<\/font><\/p>\n Documentation for the operating system or system packages.<\/font><\/p>\n \/usr\/share\/factory\/etc\/<\/font><\/p>\n Repository for vendor\u2212supplied default configuration files. This directory should be populated with pristine vendor versions of all configuration files that may be placed in \/etc\/. This is useful to compare the local configuration of a system with vendor defaults and to populate the local configuration with defaults.<\/font><\/p>\n \/usr\/share\/factory\/var\/<\/font><\/p>\n Similar to \/usr\/share\/factory\/etc\/, but for vendor versions of files in the variable, persistent data directory \/var\/.<\/font><\/p>\n \/var\/<\/font><\/p>\n Persistent, variable system data. Must be writable. This directory might be pre\u2212populated with vendor\u2212supplied data, but applications should be able to reconstruct necessary files and directories in this subhierarchy should they be missing, as the system might start up without this directory being populated. Persistency is recommended, but optional, to support ephemeral systems. This directory might become available or writable only very late during boot. Components that are required to operate during early boot hence shall not unconditionally rely on this directory.<\/font><\/p>\n \/var\/cache\/<\/font><\/p>\n Persistent system cache data. System components may place non\u2212essential data in this directory. Flushing this directory should have no effect on operation of programs, except for increased runtimes necessary to rebuild these caches.<\/font><\/p>\n \/var\/lib\/<\/font><\/p>\n Persistent system data. System components may place private data in this directory.<\/font><\/p>\n \/var\/log\/<\/font><\/p>\n Persistent system logs. System components may place private logs in this directory, though it is recommended to do most logging via the syslog<\/b>(3) and sd_journal_print<\/b>(3) calls.<\/font><\/p>\n \/var\/spool\/<\/font><\/p>\n Persistent system spool data, such as printer or mail queues.<\/font><\/p>\n \/var\/tmp\/<\/font><\/p>\n The place for larger and persistent temporary files. In contrast to \/tmp\/, this directory is usually mounted from a persistent physical file system and can thus accept larger files. (Use \/tmp\/ for smaller files.) This directory is generally not flushed at boot\u2212up, but time\u2212based cleanup of files that have not been accessed for a certain time is applied. The same security restrictions as with \/tmp\/ apply, and hence only mkstemp<\/b>(3), mkdtemp<\/b>(3) or similar calls should be used to make use of this directory. If applications find the environment variable $TMPDIR<\/i> set, they should prefer using the directory specified in it over directly referencing \/var\/tmp\/ (see environ<\/b>(7) for details). For further details about this directory, see<\/font> Using \/tmp\/ And \/var\/tmp\/ Safely<\/font><\/b> [5]<\/font><\/small> .<\/font><\/p>\n \/dev\/<\/font><\/p>\n 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<\/b>(8), and should not be written to by other components. A number of special purpose virtual file systems might be mounted below this directory.<\/font><\/p>\n \/dev\/shm\/<\/font><\/p>\n Place for POSIX shared memory segments, as created via shm_open<\/b>(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<\/i> (for user programs) instead of POSIX shared memory segments, since these directories are not world\u2212writable and hence not vulnerable to security\u2212sensitive name clashes.<\/font><\/p>\n \/proc\/<\/font><\/p>\n 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<\/b>(5). A number of special purpose virtual file systems might be mounted below this directory.<\/font><\/p>\n \/proc\/sys\/<\/font><\/p>\n 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<\/b>(5) files. In sandboxed\/containerized setups, this directory is generally mounted read\u2212only.<\/font><\/p>\n \/sys\/<\/font><\/p>\n 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\u2212only. A number of special purpose virtual file systems might be mounted below this directory.<\/font><\/p>\n \/bin\/, \/sbin\/, \/usr\/sbin\/<\/font><\/p>\n These compatibility symlinks point to \/usr\/bin\/, ensuring that scripts and binaries referencing these legacy paths correctly find their binaries.<\/font><\/p>\n \/lib\/<\/font><\/p>\n This compatibility symlink points to \/usr\/lib\/, ensuring that programs referencing this legacy path correctly find their resources.<\/font><\/p>\n \/lib64\/<\/font><\/p>\n On some architecture ABIs, this compatibility symlink points to $libdir<\/i>, ensuring that binaries referencing this legacy path correctly find their dynamic loader. This symlink only exists on architectures whose ABI places the dynamic loader in this path.<\/font><\/p>\n
DESCRIPTION<\/a>
GENERAL STRUCTURE<\/a>
RUNTIME DATA<\/a>
VENDOR\u2212SUPPLIED OPERATING SYSTEM RESOURCES<\/a>
PERSISTENT VARIABLE SYSTEM DATA<\/a>
VIRTUAL KERNEL AND API FILE SYSTEMS<\/a>
COMPATIBILITY SYMLINKS<\/a>
HOME DIRECTORY<\/a>
UNPRIVILEGED WRITE ACCESS<\/a>
NODE TYPES<\/a>
SYSTEM PACKAGES<\/a>
USER PACKAGES<\/a>
SEE ALSO<\/a>
NOTES<\/a> <\/p>\n
\nNAME <\/a> <\/h2>\n
DESCRIPTION <\/a> <\/h2>\n
GENERAL STRUCTURE <\/a> <\/h2>\n
RUNTIME DATA <\/a> <\/h2>\n
VENDOR\u2212SUPPLIED OPERATING SYSTEM RESOURCES <\/a> <\/h2>\n
PERSISTENT VARIABLE SYSTEM DATA <\/a> <\/h2>\n
VIRTUAL KERNEL AND API FILE SYSTEMS <\/a> <\/h2>\n
COMPATIBILITY SYMLINKS <\/a> <\/h2>\n