From 4160043a0fac8b812905b7502ce34adf3af538f1 Mon Sep 17 00:00:00 2001 From: Luke Shumaker Date: Tue, 6 Sep 2016 02:27:18 -0400 Subject: move man pages to appropriate directories --- man/sys/file-hierarchy.xml | 815 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 815 insertions(+) create mode 100644 man/sys/file-hierarchy.xml (limited to 'man/sys/file-hierarchy.xml') diff --git a/man/sys/file-hierarchy.xml b/man/sys/file-hierarchy.xml new file mode 100644 index 0000000000..538a592f8d --- /dev/null +++ b/man/sys/file-hierarchy.xml @@ -0,0 +1,815 @@ + + + + + + + + + file-hierarchy + systemd + + + + Developer + Lennart + Poettering + lennart@poettering.net + + + + + + file-hierarchy + 7 + + + + file-hierarchy + File system hierarchy overview + + + + Description + + Operating systems using the + systemd1 + 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 specification and + hier7. + This manual page describes a more minimal, modernized subset of + these specifications that defines more strictly the suggestions + and restrictions systemd makes on the file system + hierarchy. + + Many of the paths described here can be queried + with the + systemd-path1 + tool. + + + + General Structure + + + + / + The file system root. Usually writable, but + this is not required. Possibly a temporary file system + (tmpfs). Not shared with other hosts + (unless read-only). + + + + /boot + The boot partition used for bringing up the + system. On EFI systems, this is possibly the EFI System + Partition, also see + systemd-gpt-auto-generator8. + This directory is usually strictly local to the host, and + should be considered read-only, 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. + + + + /etc + System-specific configuration. This directory + may or may not be read-only. Frequently, this directory is + pre-populated with vendor-supplied 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. + + + + /home + The location for normal user's home + directories. Possibly shared with other systems, and never + read-only. 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-functionality + 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-user $HOME + environment variable, or via the home directory field of the + user database. + + + + /root + 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. + + + + /srv + 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. + + + + /tmp + 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 + mkstemp3, + mkdtemp3 + and related calls. This directory is usually flushed at + boot-up. Also, files that are not accessed within a certain + time are usually automatically deleted. If applications find + the environment variable $TMPDIR set, they + should prefer using the directory specified in it over + directly referencing /tmp (see + environ7 + and + IEEE + Std 1003.1 for details). + + + + + + + Runtime Data + + + + /run + 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. + + + + /run/log + Runtime system logs. System components may + place private logs in this directory. Always writable, even + when /var/log might not be accessible + yet. + + + + /run/user + Contains per-user 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 environment variable, as + documented in the XDG + Base Directory Specification. + + + + + + Vendor-supplied Operating System Resources + + + + + /usr + Vendor-supplied operating system resources. + Usually read-only, 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-supplied packages. + + + + /usr/bin + Binaries and executables for user commands + that shall appear in the $PATH 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. + + + + /usr/include + C and C++ API header files of system + libraries. + + + + /usr/lib + Static, private vendor data that is compatible + with all architectures (though not necessarily + architecture-independent). 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 (see below), + instead. + + + + /usr/lib/arch-id + Location for placing dynamic libraries into, also + called $libdir. The architecture identifier + to use is defined on Multiarch + Architecture Specifiers (Tuples) list. Legacy + locations of $libdir are + /usr/lib, + /usr/lib64. This directory should not be + used for package-specific data, unless this data is + architecture-dependent, too. To query + $libdir for the primary architecture of the + system, invoke: + # systemd-path system-library-arch + + + + + /usr/share + 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. + + + + /usr/share/doc + Documentation for the operating system or + system packages. + + + + /usr/share/factory/etc + Repository for vendor-supplied 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. + + + + /usr/share/factory/var + + Similar to + /usr/share/factory/etc, but for vendor + versions of files in the variable, persistent data directory + /var. + + + + + + + Persistent Variable System Data + + + + /var + Persistent, variable system data. Must be + writable. This directory might be pre-populated with + vendor-supplied 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. + + + + /var/cache + Persistent system cache data. System + components may place non-essential data in this directory. + Flushing this directory should have no effect on operation of + programs, except for increased runtimes necessary to rebuild + these caches. + + + + /var/lib + Persistent system data. System components may + place private data in this directory. + + + + /var/log + Persistent system logs. System components may + place private logs in this directory, though it is recommended + to do most logging via the + syslog3 + and + sd_journal_print3 + calls. + + + + /var/spool + Persistent system spool data, such as printer + or mail queues. + + + + /var/tmp + 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-up, but time-based 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 + mkstemp3, + mkdtemp3 + or similar calls should be used to make use of this directory. + If applications find the environment variable + $TMPDIR set, they should prefer using the + directory specified in it over directly referencing + /var/tmp (see + environ7 + for details). + + + + + + + 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-udevd8, + 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_open3. + 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 + proc5. + 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.d5 + 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. + + + + + + + Compatibility Symlinks + + + + /bin + /sbin + /usr/sbin + + These compatibility symlinks point to + /usr/bin, ensuring that scripts and + binaries referencing these legacy paths correctly find their + binaries. + + + + /lib + + This compatibility symlink points to + /usr/lib, ensuring that programs + referencing this legacy path correctly find their + resources. + + + + /lib64 + + On some architecture ABIs, this compatibility + symlink points to $libdir, 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. + + + + /var/run + + This compatibility symlink points to + /run, ensuring that programs referencing + this legacy path correctly find their runtime + data. + + + + + + + Home Directory + + User applications may want to place files and directories in + the user's home directory. They should follow the following basic + structure. Note that some of these directories are also + standardized (though more weakly) by the XDG + Base Directory Specification. Additional locations for + high-level user resources are defined by xdg-user-dirs. + + + + ~/.cache + + Persistent user cache data. User programs may + place non-essential data in this directory. Flushing this + directory should have no effect on operation of programs, + except for increased runtimes necessary to rebuild these + caches. If an application finds + $XDG_CACHE_HOME set, it should use the + directory specified in it instead of this + directory. + + + + ~/.config + + Application configuration and state. When a + new user is created, this directory will be empty or not exist + at all. Applications should fall back to defaults should their + configuration or state in this directory be missing. If an + application finds $XDG_CONFIG_HOME set, it + should use the directory specified in it instead of this + directory. + + + + ~/.local/bin + + Executables that shall appear in the user's + $PATH search path. It is recommended not to + place executables in this directory that are not useful for + invocation from a shell; these should be placed in a + subdirectory of ~/.local/lib instead. + Care should be taken when placing architecture-dependent + binaries in this place, which might be problematic if the home + directory is shared between multiple hosts with different + architectures. + + + + ~/.local/lib + + Static, private vendor data that is compatible + with all architectures. + + + + ~/.local/lib/arch-id + + Location for placing public dynamic libraries. + The architecture identifier to use is defined on Multiarch + Architecture Specifiers (Tuples) + list. + + + + ~/.local/share + + Resources shared between multiple packages, + such as fonts or artwork. Usually, the precise location and + format of files stored below this directory is subject to + specifications that ensure interoperability. If an application + finds $XDG_DATA_HOME set, it should use the + directory specified in it instead of this + directory. + + + + + + + + Unprivileged Write Access + + Unprivileged processes generally lack write access to most + of the hierarchy. + + The exceptions for normal users are + /tmp, + /var/tmp, + /dev/shm, as well as the home directory + $HOME (usually found below + /home) and the runtime directory + $XDG_RUNTIME_DIR (found below + /run/user) of the user, which are all + writable. + + For unprivileged system processes, only + /tmp, + /var/tmp and + /dev/shm are writable. If an + unprivileged system process needs a private writable directory in + /var or /run, it is + recommended to either create it before dropping privileges in the + daemon code, to create it via + tmpfiles.d5 + fragments during boot, or via the + RuntimeDirectory= directive of service units + (see + systemd.unit5 + for details). + + + + Node Types + + Unix file systems support different types of file nodes, + including regular files, directories, symlinks, character and + block device nodes, sockets and FIFOs. + + It is strongly recommended that /dev is + the only location below which device nodes shall be placed. + Similarly, /run shall be the only location to + place sockets and FIFOs. Regular files, directories and symlinks + may be used in all directories. + + + + System Packages + + Developers of system packages should follow strict rules + when placing their own files in the file system. The following + table lists recommended locations for specific types of files + supplied by the vendor. + + + System Package Vendor Files Locations + + + + + + Directory + Purpose + + + + + /usr/bin + Package executables that shall appear in the $PATH executable search path, compiled for any of the supported architectures compatible with the operating system. It is not recommended to place internal binaries or binaries that are not commonly invoked from the shell in this directory, such as daemon binaries. As this directory is shared with most other packages of the system, special care should be taken to pick unique names for files placed here, that are unlikely to clash with other package's files. + + + /usr/lib/arch-id + Public shared libraries of the package. As above, be careful with using too generic names, and pick unique names for your libraries to place here to avoid name clashes. + + + /usr/lib/package + Private static vendor resources of the package, including private binaries and libraries, or any other kind of read-only vendor data. + + + /usr/lib/arch-id/package + Private other vendor resources of the package that are architecture-specific and cannot be shared between architectures. Note that this generally does not include private executables since binaries of a specific architecture may be freely invoked from any other supported system architecture. + + + /usr/include/package + Public C/C++ APIs of public shared libraries of the package. + + + +
+ + Additional static vendor files may be installed in the + /usr/share hierarchy to the locations + defined by the various relevant specifications. + + During runtime, and for local configuration and state, + additional directories are defined: + + + System Package Variable Files Locations + + + + + + Directory + Purpose + + + + + /etc/package + System-specific configuration for the package. It is recommended to default to safe fallbacks if this configuration is missing, if this is possible. Alternatively, a tmpfiles.d5 fragment may be used to copy or symlink the necessary files and directories from /usr/share/factory during boot, via the L or C directives. + + + /run/package + Runtime data for the package. Packages must be able to create the necessary subdirectories in this tree on their own, since the directory is flushed automatically on boot. Alternatively, a tmpfiles.d5 fragment may be used to create the necessary directories during boot. Alternatively, the RuntimeDirectory= directive of service units may be used (see systemd.unit5 for details.) + + + /run/log/package + Runtime log data for the package. As above, the package needs to make sure to create this directory if necessary, as it will be flushed on every boot. + + + /var/cache/package + Persistent cache data of the package. If this directory is flushed, the application should work correctly on next invocation, though possibly slowed down due to the need to rebuild any local cache files. The application must be capable of recreating this directory should it be missing and necessary. + + + /var/lib/package + Persistent private data of the package. This is the primary place to put persistent data that does not fall into the other categories listed. Packages should be able to create the necessary subdirectories in this tree on their own, since the directory might be missing on boot. Alternatively, a tmpfiles.d5 fragment may be used to create the necessary directories during boot. + + + /var/log/package + Persistent log data of the package. As above, the package should make sure to create this directory if necessary, as it might be missing. + + + /var/spool/package + Persistent spool/queue data of the package. As above, the package should make sure to create this directory if necessary, as it might be missing. + + + +
+ + + + User Packages + + Programs running in user context should follow strict rules + when placing their own files in the user's home directory. The + following table lists recommended locations in the home directory + for specific types of files supplied by the vendor if the + application is installed in the home directory. (Note, however, + that user applications installed system-wide should follow the + rules outlined above regarding placing vendor files.) + + + User Package Vendor File Locations + + + + + + Directory + Purpose + + + + + ~/.local/bin + Package executables that shall appear in the $PATH executable search path. It is not recommended to place internal executables or executables that are not commonly invoked from the shell in this directory, such as daemon executables. As this directory is shared with most other packages of the user, special care should be taken to pick unique names for files placed here, that are unlikely to clash with other package's files. + + + ~/.local/lib/arch-id + Public shared libraries of the package. As above, be careful with using too generic names, and pick unique names for your libraries to place here to avoid name clashes. + + + ~/.local/lib/package + Private, static vendor resources of the package, compatible with any architecture, or any other kind of read-only vendor data. + + + ~/.local/lib/arch-id/package + Private other vendor resources of the package that are architecture-specific and cannot be shared between architectures. + + + +
+ + Additional static vendor files may be installed in the + ~/.local/share hierarchy to the locations + defined by the various relevant specifications. + + During runtime, and for local configuration and state, + additional directories are defined: + + + User Package Variable File Locations + + + + + + Directory + Purpose + + + + + ~/.config/package + User-specific configuration and state for the package. It is required to default to safe fallbacks if this configuration is missing. + + + $XDG_RUNTIME_DIR/package + User runtime data for the package. + + + ~/.cache/package + Persistent cache data of the package. If this directory is flushed, the application should work correctly on next invocation, though possibly slowed down due to the need to rebuild any local cache files. The application must be capable of recreating this directory should it be missing and necessary. + + + +
+ + + + See Also + + systemd1, + hier7, + systemd-path1, + systemd-gpt-auto-generator8, + sysctl.d5, + tmpfiles.d5, + pkg-config1, + systemd.unit5 + + + + -- cgit v1.2.3-54-g00ecf