--- name: "mount_setattr" section: "2" platform: "linux" package: "man-pages" version: "6.19-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/mount_setattr" --- # mount\_setattr(2) change properties of a mount or mount tree ## NAME mount\_setattr - change properties of a mount or mount tree ## LIBRARY Standard C library (*libc*, *-lc*) ## SYNOPSIS ``` #include /* Definition of AT_* constants */ #include ``` **int mount\_setattr(int** *dirfd***, const char \****path***, unsigned int** *flags***,** **struct mount\_attr \****attr***, size\_t** *size***);** ## DESCRIPTION The **mount\_setattr**() system call is part of the suite of file-descriptor-based mount facilities in Linux. **mount\_setattr**() changes the mount properties of a mount or an entire mount tree. If *path* is relative, then it is interpreted relative to the directory referred to by the file descriptor *dirfd*. If *dirfd* is the special value **AT\_FDCWD**, then *path* is interpreted relative to the current working directory of the calling process. If *path* is the empty string and **AT\_EMPTY\_PATH** is specified in *flags*, then the mount properties of the mount identified by *dirfd* are changed. (See [**openat**(2)](/openat/2.md) for an explanation of why the *dirfd* argument is useful.) The **mount\_setattr**() system call uses an extensible structure (*struct mount\_attr*) to allow for future extensions. Any non-flag extensions to **mount\_setattr**() will be implemented as new fields appended to the this structure, with a zero value in a new field resulting in the kernel behaving as though that extension field was not present. Therefore, the caller *must* zero-fill this structure on initialization. See the "Extensibility" subsection under **NOTES** for more details. The *size* argument should usually be specified as *sizeof(struct mount\_attr)*. However, if the caller is using a kernel that supports an extended *struct mount\_attr*, but the caller does not intend to make use of these features, it is possible to pass the size of an earlier version of the structure together with the extended structure. This allows the kernel to not copy later parts of the structure that aren't used anyway. With each extension that changes the size of *struct mount\_attr*, the kernel will expose a definition of the form **MOUNT\_ATTR\_SIZE\_VER***number* . For example, the macro for the size of the initial version of *struct mount\_attr* is **MOUNT\_ATTR\_SIZE\_VER0**. The *flags* argument can be used to alter the pathname resolution behavior. The supported values are: - **AT\_EMPTY\_PATH** If *path* is the empty string, change the mount properties on *dirfd* itself. - **AT\_RECURSIVE** Change the mount properties of the entire mount tree. - **AT\_SYMLINK\_NOFOLLOW** Don't follow trailing symbolic links. - **AT\_NO\_AUTOMOUNT** Don't trigger automounts. The *attr* argument of **mount\_setattr**() is a pointer to a *mount\_attr* structure, described in [**mount\_attr**(2type)](/mount_attr/2type.md). The *attr\_set* and *attr\_clr* members are used to specify the mount properties that are supposed to be set or cleared for a mount or mount tree. Flags set in *attr\_set* enable a property on a mount or mount tree, and flags set in *attr\_clr* remove a property from a mount or mount tree. When changing mount properties, the kernel will first clear the flags specified in the *attr\_clr* field, and then set the flags specified in the *attr\_set* field. For example, these settings: ``` struct mount_attr attr = { .attr_clr = MOUNT_ATTR_NOEXEC | MOUNT_ATTR_NODEV, .attr_set = MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID, }; ``` are equivalent to the following steps: ``` unsigned int current_mnt_flags = mnt->mnt_flags; /* * Clear all flags set in .attr_clr, * clearing MOUNT_ATTR_NOEXEC and MOUNT_ATTR_NODEV. */ current_mnt_flags &= ~attr->attr_clr; /* * Now set all flags set in .attr_set, * applying MOUNT_ATTR_RDONLY and MOUNT_ATTR_NOSUID. */ current_mnt_flags |= attr->attr_set; mnt->mnt_flags = current_mnt_flags; ``` As a result of this change, the mount or mount tree (a) is read-only; (b) blocks the execution of set-user-ID and set-group-ID programs; (c) allows execution of programs; and (d) allows access to devices. Multiple changes with the same set of flags requested in *attr\_clr* and *attr\_set* are guaranteed to be idempotent after the changes have been applied. The following mount attributes can be specified in the *attr\_set* or *attr\_clr* fields: - **MOUNT\_ATTR\_RDONLY** If set in *attr\_set*, makes the mount read-only. If set in *attr\_clr*, removes the read-only setting if set on the mount. - **MOUNT\_ATTR\_NOSUID** If set in *attr\_set*, causes the mount not to honor the set-user-ID and set-group-ID mode bits and file capabilities when executing programs. If set in *attr\_clr*, clears the set-user-ID, set-group-ID, and file capability restriction if set on this mount. - **MOUNT\_ATTR\_NODEV** If set in *attr\_set*, prevents access to devices on this mount. If set in *attr\_clr*, removes the restriction that prevented accessing devices on this mount. - **MOUNT\_ATTR\_NOEXEC** If set in *attr\_set*, prevents executing programs on this mount. If set in *attr\_clr*, removes the restriction that prevented executing programs on this mount. - **MOUNT\_ATTR\_NOSYMFOLLOW** If set in *attr\_set*, prevents following symbolic links on this mount. If set in *attr\_clr*, removes the restriction that prevented following symbolic links on this mount. - **MOUNT\_ATTR\_NODIRATIME** If set in *attr\_set*, prevents updating access time for directories on this mount. If set in *attr\_clr*, removes the restriction that prevented updating access time for directories. Note that **MOUNT\_ATTR\_NODIRATIME** can be combined with other access-time settings and is implied by the noatime setting. All other access-time settings are mutually exclusive. - **MOUNT\_ATTR\_\_ATIME** - changing access-time settings The access-time values listed below are an enumeration that includes the value zero, expressed in the bits defined by the mask **MOUNT\_ATTR\_\_ATIME**. Even though these bits are an enumeration (in contrast to the other mount flags such as **MOUNT\_ATTR\_NOEXEC**), they are nonetheless passed in *attr\_set* and *attr\_clr* for consistency with [**fsmount**(2)](/fsmount/2.md), which introduced this behavior. - Note that, since the access-time values are an enumeration rather than bit values, a caller wanting to transition to a different access-time setting cannot simply specify the access-time setting in *attr\_set*, but must also include **MOUNT\_ATTR\_\_ATIME** in the *attr\_clr* field. The kernel will verify that **MOUNT\_ATTR\_\_ATIME** isn't partially set in *attr\_clr* (i.e., either all bits in the **MOUNT\_ATTR\_\_ATIME** bit field are either set or clear), and that *attr\_set* doesn't have any access-time bits set if **MOUNT\_ATTR\_\_ATIME** isn't set in *attr\_clr*. - **MOUNT\_ATTR\_RELATIME** When a file is accessed via this mount, update the file's last access time (atime) only if the current value of atime is less than or equal to the file's last modification time (mtime) or last status change time (ctime). - To enable this access-time setting on a mount or mount tree, **MOUNT\_ATTR\_RELATIME** must be set in *attr\_set* and **MOUNT\_ATTR\_\_ATIME** must be set in the *attr\_clr* field. - **MOUNT\_ATTR\_NOATIME** Do not update access times for (all types of) files on this mount. - To enable this access-time setting on a mount or mount tree, **MOUNT\_ATTR\_NOATIME** must be set in *attr\_set* and **MOUNT\_ATTR\_\_ATIME** must be set in the *attr\_clr* field. - **MOUNT\_ATTR\_STRICTATIME** Always update the last access time (atime) when files are accessed on this mount. - To enable this access-time setting on a mount or mount tree, **MOUNT\_ATTR\_STRICTATIME** must be set in *attr\_set* and **MOUNT\_ATTR\_\_ATIME** must be set in the *attr\_clr* field. - **MOUNT\_ATTR\_IDMAP** If set in *attr\_set*, creates an ID-mapped mount. The ID mapping is taken from the user namespace specified in *userns\_fd* and attached to the mount. - Since it is not supported to change the ID mapping of a mount after it has been ID mapped, it is invalid to specify **MOUNT\_ATTR\_IDMAP** in *attr\_clr*. - For further details, see the subsection "ID-mapped mounts" under NOTES. The *propagation* field is used to specify the propagation type of the mount or mount tree. This field either has the value zero, meaning leave the propagation type unchanged, or it has one of the following values: - **MS\_PRIVATE** Turn all mounts into private mounts. - **MS\_SHARED** Turn all mounts into shared mounts. - **MS\_SLAVE** Turn all mounts into dependent mounts. - **MS\_UNBINDABLE** Turn all mounts into unbindable mounts. For further details on the above propagation types, see [**mount\_namespaces**(7)](/mount_namespaces/7.md). ## RETURN VALUE On success, **mount\_setattr**() returns zero. On error, -1 is returned and *errno* is set to indicate the error. ## ERRORS - **EBADF** *path* is relative but *dirfd* is neither **AT\_FDCWD** nor a valid file descriptor. - **EBADF** *userns\_fd* is not a valid file descriptor. - **EBUSY** The caller tried to change the mount to **MOUNT\_ATTR\_RDONLY**, but the mount still holds files open for writing. - **EBUSY** The caller tried to create an ID-mapped mount raising **MOUNT\_ATTR\_IDMAP** and specifying *userns\_fd* but the mount still holds files open for writing. - **EINVAL** The pathname specified via the *dirfd* and *path* arguments to **mount\_setattr**() isn't a mount point. - **EINVAL** An unsupported value was set in *flags*. - **EINVAL** An unsupported value was specified in the *attr\_set* field of *mount\_attr*. - **EINVAL** An unsupported value was specified in the *attr\_clr* field of *mount\_attr*. - **EINVAL** An unsupported value was specified in the *propagation* field of *mount\_attr*. - **EINVAL** More than one of **MS\_SHARED**, **MS\_SLAVE**, **MS\_PRIVATE**, or **MS\_UNBINDABLE** was set in the *propagation* field of *mount\_attr*. - **EINVAL** An access-time setting was specified in the *attr\_set* field without **MOUNT\_ATTR\_\_ATIME** being set in the *attr\_clr* field. - **EINVAL** **MOUNT\_ATTR\_IDMAP** was specified in *attr\_clr*. - **EINVAL** A file descriptor value was specified in *userns\_fd* which exceeds **INT\_MAX**. - **EINVAL** A valid file descriptor value was specified in *userns\_fd*, but the file descriptor did not refer to a user namespace. - **EINVAL** The underlying filesystem does not support ID-mapped mounts. - **EINVAL** The mount that is to be ID mapped is not a detached mount; that is, the mount has not previously been visible in a mount namespace. - **EINVAL** A partial access-time setting was specified in *attr\_clr* instead of **MOUNT\_ATTR\_\_ATIME** being set. - **EINVAL** The mount is located outside the caller's mount namespace. - **EINVAL** The underlying filesystem has been mounted in a mount namespace that is owned by a noninitial user namespace - **ENOENT** A pathname was empty or had a nonexistent component. - **ENOMEM** When changing mount propagation to **MS\_SHARED**, a new peer group ID needs to be allocated for all mounts without a peer group ID set. This allocation failed because there was not enough memory to allocate the relevant internal structures. - **ENOSPC** When changing mount propagation to **MS\_SHARED**, a new peer group ID needs to be allocated for all mounts without a peer group ID set. This allocation failed because the kernel has run out of IDs. - **EPERM** One of the mounts had at least one of **MOUNT\_ATTR\_NOATIME**, **MOUNT\_ATTR\_NODEV**, **MOUNT\_ATTR\_NODIRATIME**, **MOUNT\_ATTR\_NOEXEC**, **MOUNT\_ATTR\_NOSUID**, or **MOUNT\_ATTR\_RDONLY** set and the flag is locked. Mount attributes become locked on a mount if: - • A new mount or mount tree is created causing mount propagation across user namespaces (i.e., propagation to a mount namespace owned by a different user namespace). The kernel will lock the aforementioned flags to prevent these sensitive properties from being altered. - • A new mount and user namespace pair is created. This happens for example when specifying **CLONE\_NEWUSER \| CLONE\_NEWNS** in [**unshare**(2)](/unshare/2.md), [**clone**(2)](/clone/2.md), or [**clone3**(2)](/clone3/2.md). The aforementioned flags become locked in the new mount namespace to prevent sensitive mount properties from being altered. Since the newly created mount namespace will be owned by the newly created user namespace, a calling process that is privileged in the new user namespace would—in the absence of such locking—be able to alter sensitive mount properties (e.g., to remount a mount that was marked read-only as read-write in the new mount namespace). - **EPERM** A valid file descriptor value was specified in *userns\_fd*, but the file descriptor refers to the initial user namespace. - **EPERM** An attempt was made to add an ID mapping to a mount that is already ID mapped. - **EPERM** The caller does not have **CAP\_SYS\_ADMIN** in the initial user namespace. ## STANDARDS Linux. ## HISTORY Linux 5.12, glibc 2.36. ## NOTES ### ID-mapped mounts Creating an ID-mapped mount makes it possible to change the ownership of all files located under a mount. Thus, ID-mapped mounts make it possible to change ownership in a temporary and localized way. It is a localized change because the ownership changes are visible only via a specific mount. All other users and locations where the filesystem is exposed are unaffected. It is a temporary change because the ownership changes are tied to the lifetime of the mount. Whenever callers interact with the filesystem through an ID-mapped mount, the ID mapping of the mount will be applied to user and group IDs associated with filesystem objects. This encompasses the user and group IDs associated with inodes and also the following [**xattr**(7)](/xattr/7.md) keys: - • *security.capability*, whenever filesystem capabilities are stored or returned in the **VFS\_CAP\_REVISION\_3** format, which stores a root user ID alongside the capabilities (see [**capabilities**(7)](/capabilities/7.md)). - • *system.posix\_acl\_access* and *system.posix\_acl\_default*, whenever user IDs or group IDs are stored in **ACL\_USER** or **ACL\_GROUP** entries. The following conditions must be met in order to create an ID-mapped mount: - • The caller must have the **CAP\_SYS\_ADMIN** capability in the user namespace the filesystem was mounted in. - • The underlying filesystem must support ID-mapped mounts. Currently, the following filesystems support ID-mapped mounts: - • [**xfs**(5)](/xfs/5.md) (since Linux 5.12) - • [**ext4**(5)](/ext4/5.md) (since Linux 5.12) - • **FAT** (since Linux 5.12) - • [**btrfs**(5)](/btrfs/5.md) (since Linux 5.15) - • **ntfs3** (since Linux 5.15) - • **f2fs** (since Linux 5.18) - • **erofs** (since Linux 5.19) - • **overlayfs** (ID-mapped lower and upper layers supported since Linux 5.19) - • **squashfs** (since Linux 6.2) - • **tmpfs** (since Linux 6.3) - • **cephfs** (since Linux 6.7) - • **hugetlbfs** (since Linux 6.9) - • The mount must not already be ID-mapped. This also implies that the ID mapping of a mount cannot be altered. - • The mount must not have any writers. - • The mount must be a detached mount; that is, it must have been created by calling [**open\_tree**(2)](/open_tree/2.md) with the **OPEN\_TREE\_CLONE** flag and it must not already have been visible in a mount namespace. (To put things another way: the mount must not have been attached to the filesystem hierarchy with a system call such as [**move\_mount**(2)](/move_mount/2.md).) ID mappings can be created for user IDs, group IDs, and project IDs. An ID mapping is essentially a mapping of a range of user or group IDs into another or the same range of user or group IDs. ID mappings are written to map files as three numbers separated by white space. The first two numbers specify the starting user or group ID in each of the two user namespaces. The third number specifies the range of the ID mapping. For example, a mapping for user IDs such as "1000 1001 1" would indicate that user ID 1000 in the caller's user namespace is mapped to user ID 1001 in its ancestor user namespace. Since the map range is 1, only user ID 1000 is mapped. It is possible to specify up to 340 ID mappings for each ID mapping type. If any user IDs or group IDs are not mapped, all files owned by that unmapped user or group ID will appear as being owned by the overflow user ID or overflow group ID respectively. Further details on setting up ID mappings can be found in [**user\_namespaces**(7)](/user_namespaces/7.md). In the common case, the user namespace passed in *userns\_fd* (together with **MOUNT\_ATTR\_IDMAP** in *attr\_set*) to create an ID-mapped mount will be the user namespace of a container. In other scenarios it will be a dedicated user namespace associated with a user's login session as is the case for portable home directories in [**systemd-homed.service**(8)](/systemd-homed.service/8.md)). It is also perfectly fine to create a dedicated user namespace for the sake of ID mapping a mount. ID-mapped mounts can be useful in the following and a variety of other scenarios: - • Sharing files or filesystems between multiple users or multiple machines, especially in complex scenarios. For example, ID-mapped mounts are used to implement portable home directories in [**systemd-homed.service**(8)](/systemd-homed.service/8.md), where they allow users to move their home directory to an external storage device and use it on multiple computers where they are assigned different user IDs and group IDs. This effectively makes it possible to assign random user IDs and group IDs at login time. - • Sharing files or filesystems from the host with unprivileged containers. This allows a user to avoid having to change ownership permanently through [**chown**(2)](/chown/2.md). - • ID mapping a container's root filesystem. Users don't need to change ownership permanently through [**chown**(2)](/chown/2.md). Especially for large root filesystems, using [**chown**(2)](/chown/2.md) can be prohibitively expensive. - • Sharing files or filesystems between containers with non-overlapping ID mappings. - • Implementing discretionary access (DAC) permission checking for filesystems lacking a concept of ownership. - • Efficiently changing ownership on a per-mount basis. In contrast to [**chown**(2)](/chown/2.md), changing ownership of large sets of files is instantaneous with ID-mapped mounts. This is especially useful when ownership of an entire root filesystem of a virtual machine or container is to be changed as mentioned above. With ID-mapped mounts, a single **mount\_setattr**() system call will be sufficient to change the ownership of all files. - • Taking the current ownership into account. ID mappings specify precisely what a user or group ID is supposed to be mapped to. This contrasts with the [**chown**(2)](/chown/2.md) system call which cannot by itself take the current ownership of the files it changes into account. It simply changes the ownership to the specified user ID and group ID. - • Locally and temporarily restricted ownership changes. ID-mapped mounts make it possible to change ownership locally, restricting the ownership changes to specific mounts, and temporarily as the ownership changes only apply as long as the mount exists. By contrast, changing ownership via the [**chown**(2)](/chown/2.md) system call changes the ownership globally and permanently. ### Mount attributes and filesystem parameters Some mount attributes (traditionally associated with [**mount**(8)](/mount/8.md)-style options) have a sibling filesystem parameter with superficially similar user-facing behavior. For example, the *-o ro* option to [**mount**(8)](/mount/8.md) can refer to the "read-only" filesystem parameter, or the "read-only" mount attribute. Both of these result in mount objects becoming read-only, but they do have different behavior. The distinction between these two kinds of option is that mount object attributes are applied per-mount-object (allowing different mount objects derived from a given filesystem instance to have different attributes), while filesystem instance parameters ("superblock flags" in kernel-developer parlance) apply to all mount objects derived from the same filesystem instance. When using [**mount**(2)](/mount/2.md), the line between these two types of mount options was blurred. However, with **mount\_setattr**() and [**fsconfig**(2)](/fsconfig/2.md), the distinction is made much clearer. Mount attributes are configured with **mount\_setattr**(), while filesystem parameters are configured using [**fsconfig**(2)](/fsconfig/2.md). ### Extensibility In order to allow for future extensibility, **mount\_setattr**() requires the user-space application to specify the size of the *mount\_attr* structure that it is passing. By providing this information, it is possible for **mount\_setattr**() to provide both forwards- and backwards-compatibility, with *size* acting as an implicit version number. (Because new extension fields will always be appended, the structure size will always increase.) This extensibility design is very similar to other system calls such as **perf\_setattr**(2), [**perf\_event\_open**(2)](/perf_event_open/2.md), [**clone3**(2)](/clone3/2.md) and [**openat2**(2)](/openat2/2.md). Let *usize* be the size of the structure as specified by the user-space application, and let *ksize* be the size of the structure which the kernel supports, then there are three cases to consider: - • If *ksize* equals *usize*, then there is no version mismatch and *attr* can be used verbatim. - • If *ksize* is larger than *usize*, then there are some extension fields that the kernel supports which the user-space application is unaware of. Because a zero value in any added extension field signifies a no-op, the kernel treats all of the extension fields not provided by the user-space application as having zero values. This provides backwards-compatibility. - • If *ksize* is smaller than *usize*, then there are some extension fields which the user-space application is aware of but which the kernel does not support. Because any extension field must have its zero values signify a no-op, the kernel can safely ignore the unsupported extension fields if they are all zero. If any unsupported extension fields are non-zero, then -1 is returned and *errno* is set to **E2BIG**. This provides forwards-compatibility. Because the definition of *struct mount\_attr* may change in the future (with new fields being added when system headers are updated), user-space applications should zero-fill *struct mount\_attr* to ensure that recompiling the program with new headers will not result in spurious errors at run time. The simplest way is to use a designated initializer: ``` struct mount_attr attr = { .attr_set = MOUNT_ATTR_RDONLY, .attr_clr = MOUNT_ATTR_NODEV }; ``` Alternatively, the structure can be zero-filled using [**memset**(3)](/memset/3.md) or similar functions: ``` struct mount_attr attr; memset(&attr, 0, sizeof(attr)); attr.attr_set = MOUNT_ATTR_RDONLY; attr.attr_clr = MOUNT_ATTR_NODEV; ``` A user-space application that wishes to determine which extensions the running kernel supports can do so by conducting a binary search on *size* with a structure which has every byte nonzero (to find the largest value which doesn't produce an error of **E2BIG**). ## EXAMPLES ``` /* * This program allows the caller to create a new detached mount * and set various properties on it. */ #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include static const struct option longopts[] = { {"map-mount", required_argument, NULL, 'a'}, {"recursive", no_argument, NULL, 'b'}, {"read-only", no_argument, NULL, 'c'}, {"block-setid", no_argument, NULL, 'd'}, {"block-devices", no_argument, NULL, 'e'}, {"block-exec", no_argument, NULL, 'f'}, {"no-access-time", no_argument, NULL, 'g'}, { NULL, 0, NULL, 0 }, }; int main(int argc, char *argv[]) { int fd_userns = -1; int fd_tree; int index = 0; int ret; bool recursive = false; const char *source; const char *target; struct mount_attr *attr = &(struct mount_attr){}; while ((ret = getopt_long_only(argc, argv, "", longopts, &index)) != -1) { switch (ret) { case 'a': fd_userns = open(optarg, O_RDONLY | O_CLOEXEC); if (fd_userns == -1) err(EXIT_FAILURE, "open(%s)", optarg); break; case 'b': recursive = true; break; case 'c': attr->attr_set |= MOUNT_ATTR_RDONLY; break; case 'd': attr->attr_set |= MOUNT_ATTR_NOSUID; break; case 'e': attr->attr_set |= MOUNT_ATTR_NODEV; break; case 'f': attr->attr_set |= MOUNT_ATTR_NOEXEC; break; case 'g': attr->attr_set |= MOUNT_ATTR_NOATIME; attr->attr_clr |= MOUNT_ATTR__ATIME; break; default: errx(EXIT_FAILURE, "Invalid argument specified"); } } if ((argc - optind) < 2) errx(EXIT_FAILURE, "Missing source or target mount point"); source = argv[optind]; target = argv[optind + 1]; /* In the following, -1 as the 'dirfd' argument ensures that open_tree() fails if 'source' is not an absolute pathname. */ fd_tree = open_tree(-1, source, OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH | (recursive ? AT_RECURSIVE : 0)); if (fd_tree == -1) err(EXIT_FAILURE, "open(%s)", source); if (fd_userns >= 0) { attr->attr_set |= MOUNT_ATTR_IDMAP; attr->userns_fd = fd_userns; } ret = mount_setattr(fd_tree, "", AT_EMPTY_PATH | (recursive ? AT_RECURSIVE : 0), attr, sizeof(struct mount_attr)); if (ret == -1) err(EXIT_FAILURE, "mount_setattr"); close(fd_userns); /* In the following, -1 as the 'to_dirfd' argument ensures that open_tree() fails if 'target' is not an absolute pathname. */ ret = move_mount(fd_tree, "", -1, target, MOVE_MOUNT_F_EMPTY_PATH); if (ret == -1) err(EXIT_FAILURE, "move_mount() to %s", target); close(fd_tree); exit(EXIT_SUCCESS); } ``` ## SEE ALSO [**newgidmap**(1)](/newgidmap/1.md), [**newuidmap**(1)](/newuidmap/1.md), [**clone**(2)](/clone/2.md), [**mount**(2)](/mount/2.md), [**unshare**(2)](/unshare/2.md), [**proc**(5)](/proc/5.md), [**capabilities**(7)](/capabilities/7.md), [**mount\_namespaces**(7)](/mount_namespaces/7.md), [**user\_namespaces**(7)](/user_namespaces/7.md), [**xattr**(7)](/xattr/7.md)