1.\" Copyright (c) 1980, 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd January 15, 2024 29.Dt MOUNT 8 30.Os 31.Sh NAME 32.Nm mount 33.Nd mount file systems 34.Sh SYNOPSIS 35.Nm 36.Op Fl -libxo 37.Op Fl adflpruvw 38.Op Fl F Ar fstab 39.Op Fl o Ar options 40.Op Fl t Oo Cm no Oc Ns Cm Ar type Ns Op Cm , Ns Ar type ... 41.Nm 42.Op Fl -libxo 43.Op Fl dfpruvw 44.Ar special | node 45.Nm 46.Op Fl -libxo 47.Op Fl dfpruvw 48.Op Fl o Ar options 49.Op Fl t Oo Cm no Oc Ns Cm Ar type Ns Op Cm , Ns Ar type ... 50.Ar special node 51.Sh DESCRIPTION 52The 53.Nm 54utility calls the 55.Xr nmount 2 56system call to prepare and graft a 57.Ar special 58device or the remote node (rhost:path) on to the file system tree at the point 59.Ar node . 60If either 61.Ar special 62or 63.Ar node 64are not provided, the appropriate information is taken from the 65.Xr fstab 5 66file. 67.Pp 68The system maintains a list of currently mounted file systems. 69If no arguments are given to 70.Nm , 71this list is printed. 72.Pp 73The options are as follows: 74.Bl -tag -width indent 75.It Fl -libxo 76Generate output via 77.Xr libxo 3 78in a selection of different human and machine readable formats. 79See 80.Xr xo_parse_args 3 81for details on command line arguments. 82.It Fl a 83All the file systems described in 84.Xr fstab 5 85are mounted. 86Exceptions are those marked as 87.Dq Li noauto , 88those marked as 89.Dq Li late 90(unless the 91.Fl l 92option was specified), 93those excluded by the 94.Fl t 95flag (see below), or if they are already mounted (except the 96root file system which is always remounted to preserve 97traditional single user mode behavior). 98.It Fl d 99Causes everything to be done except for the actual system call. 100This option is useful in conjunction with the 101.Fl v 102flag to 103determine what the 104.Nm 105command is trying to do. 106.It Fl F Ar fstab 107Specify the 108.Pa fstab 109file to use. 110.It Fl f 111Forces the revocation of write access when trying to downgrade 112a file system mount status from read-write to read-only. 113Also 114forces the R/W mount of an unclean file system (dangerous; use with 115caution). 116.It Fl L 117When used in conjunction with the 118.Fl a 119option, mount 120.Em only 121those file systems which are marked as 122.Dq Li late . 123.It Fl l 124When used in conjunction with the 125.Fl a 126option, also mount those file systems which are marked as 127.Dq Li late . 128.It Fl n 129For compatibility with some other implementations, this flag is 130currently a no-op. 131.It Fl o 132Options are specified with a 133.Fl o 134flag followed by a comma separated string of options. 135In case of conflicting options being specified, the rightmost option 136takes effect. 137The following options are available: 138.Bl -tag -width indent 139.It Cm acls 140Enable POSIX.1e Access Control Lists, or ACLs, which can be customized via the 141.Xr setfacl 1 142and 143.Xr getfacl 1 144commands. 145This flag is mutually exclusive with 146.Cm nfsv4acls 147flag. 148.It Cm async 149All I/O to the file system should be done asynchronously. 150This is a 151.Em dangerous 152flag to set, since it does not guarantee that the file system structure 153on the disk will remain consistent. 154For this reason, the 155.Cm async 156flag should be used sparingly, and only when some data recovery 157mechanism is present. 158.It Cm automounted 159This flag indicates that the file system was mounted by 160.Xr automountd 8 . 161Automounted file systems are automatically unmounted by 162.Xr autounmountd 8 . 163.It Cm autoro 164Mount the file system read-write. 165If that fails with an error that suggests that the media could be read-only, 166then automatically try to mount the file system read-only. 167.It Cm current 168When used with the 169.Fl u 170flag, this is the same as specifying the options currently in effect for 171the mounted file system. 172.It Cm emptydir 173Require that the mount point directory be empty. 174.It Cm force 175The same as 176.Fl f ; 177forces the revocation of write access when trying to downgrade 178a file system mount status from read-write to read-only. 179Also 180forces the R/W mount of an unclean file system (dangerous; use with caution). 181.It Cm fstab 182When used with the 183.Fl u 184flag, this is the same as specifying all the options listed in the 185.Xr fstab 5 186file for the file system. 187.It Cm late 188This file system should be skipped when 189.Nm 190is run with the 191.Fl a 192flag but without the 193.Fl l 194flag. 195.It Cm mountprog Ns = Ns Aq Ar program 196Force 197.Nm 198to use the specified program to mount the file system, instead of calling 199.Xr nmount 2 200directly. 201For example: 202.Bd -literal 203mount -t foofs -o mountprog=/mydir/fooprog /dev/cd0 /mnt 204.Ed 205.It Cm multilabel 206Enable multi-label Mandatory Access Control, or MAC, on the specified file 207system. 208If the file system supports multilabel operation, individual labels will 209be maintained for each object in the file system, rather than using a 210single label for all objects. 211An alternative to the 212.Fl l 213flag in 214.Xr tunefs 8 . 215See 216.Xr mac 4 217for more information, which cause the multilabel mount flag to be set 218automatically at mount-time. 219.It Cm nfsv4acls 220Enable NFSv4 ACLs, which can be customized via the 221.Xr setfacl 1 222and 223.Xr getfacl 1 224commands. 225This flag is mutually exclusive with 226.Cm acls 227flag. 228.It Cm noasync 229Metadata I/O should be done synchronously, while data I/O should be done 230asynchronously. 231This is the default. 232.It Cm noatime 233Do not update the file access time when reading from a file. 234This option 235is useful on file systems where there are large numbers of files and 236performance is more critical than updating the file access time (which is 237rarely ever important). 238This option is currently only supported on local file systems. 239.It Cm noauto 240This file system should be skipped when 241.Nm 242is run with the 243.Fl a 244flag. 245.It Cm noclusterr 246Disable read clustering. 247.It Cm noclusterw 248Disable write clustering. 249.It Cm nocover 250Do not mount if the requested mount point is already 251the root of a mount point. 252.It Cm noexec 253Do not allow execution of any binaries on the mounted file system. 254This option is useful for a server that has file systems containing 255binaries for architectures other than its own. 256Note: This option was not designed as a security feature and no 257guarantee is made that it will prevent malicious code execution; for 258example, it is still possible to execute scripts which reside on a 259.Cm noexec 260mounted partition. 261.It Cm nosuid 262Do not allow set-user-identifier or set-group-identifier bits to take effect. 263Note: this option is worthless if a public available suid or sgid 264wrapper is installed on your system. 265It is set automatically when the user does not have super-user privileges. 266.It Cm nosymfollow 267Do not follow symlinks 268on the mounted file system. 269.It Cm ro 270The same as 271.Fl r ; 272mount the file system read-only (even the super-user may not write it). 273.It Cm snapshot 274Take a snapshot of the specified filesystem. 275When this option is used, all other options are ignored. 276The 277.Fl u 278flag is required with this option. 279.Pp 280Snapshot files must be created in the file system that is being 281snapshotted. 282You may create up to 20 snapshots per file system. 283Active snapshots are recorded in the superblock, so they persist across unmount 284and remount operations and across system reboots. 285When you are done with a snapshot, it can be removed with the 286.Xr rm 1 287command. 288Snapshots may be removed in any order, however you may not get back all the 289space contained in the snapshot as another snapshot may claim some of the blocks 290that it is releasing. 291Note that the schg flag is set on snapshots to ensure that not even the root 292user can write to them. 293The unlink command makes an exception for snapshot files in that it allows them 294to be removed even though they have the schg flag set, so it is not necessary to 295clear the schg flag before removing a snapshot file. 296.Pp 297Once you have taken a snapshot, there are three interesting things that you can 298do with it: 299.Pp 300.Bl -enum -compact 301.It 302Run 303.Xr fsck 8 304on the snapshot file. 305Assuming that the file system was clean when it was mounted, you should always 306get a clean (and unchanging) result from running fsck on the snapshot. 307This is essentially what the background fsck process does. 308.Pp 309.It 310Run 311.Xr dump 8 312on the snapshot. 313You will get a dump that is consistent with the file system as of the timestamp 314of the snapshot. 315.Pp 316.It 317Mount the snapshot as a frozen image of the file system. 318To mount the snapshot 319.Pa /var/snapshot/snap1 : 320.Bd -literal 321mdconfig -a -t vnode -f /var/snapshot/snap1 -u 4 322mount -r /dev/md4 /mnt 323.Ed 324.Pp 325You can now cruise around your frozen 326.Pa /var 327file system at 328.Pa /mnt . 329Everything will be in the same state that it was at the time the snapshot was 330taken. 331The one exception is that any earlier snapshots will appear as zero length 332files. 333When you are done with the mounted snapshot: 334.Bd -literal 335umount /mnt 336mdconfig -d -u 4 337.Ed 338.El 339.It Cm suiddir 340A directory on the mounted file system will respond to the SUID bit 341being set, by setting the owner of any new files to be the same 342as the owner of the directory. 343New directories will inherit the bit from their parents. 344Execute bits are removed from 345the file, and it will not be given to root. 346.Pp 347This feature is designed for use on fileservers serving PC users via 348ftp, SAMBA, or netatalk. 349It provides security holes for shell users and as 350such should not be used on shell machines, especially on home directories. 351This option requires the SUIDDIR 352option in the kernel to work. 353Only UFS file systems support this option. 354See 355.Xr chmod 2 356for more information. 357.It Cm sync 358All I/O to the file system should be done synchronously. 359.It Cm update 360The same as 361.Fl u ; 362indicate that the status of an already mounted file system should be changed. 363.It Cm union 364Causes the namespace at the mount point to appear as the union 365of the mounted file system root and the existing directory. 366Lookups will be done in the mounted file system first. 367If those operations fail due to a non-existent file the underlying 368directory is then accessed. 369All creates are done in the mounted file system. 370.It Cm untrusted 371The file system is untrusted and the kernel should use more 372extensive checks on the file-system's metadata before using it. 373This option is intended to be used when mounting file systems 374from untrusted media such as USB memory sticks or other 375externally-provided media. 376.El 377.Pp 378Any additional options specific to a file system type that is not 379one of the internally known types (see the 380.Fl t 381option) may be passed as a comma separated list; these options are 382distinguished by a leading 383.Dq \&- 384(dash). 385For example, the 386.Nm 387command: 388.Bd -literal -offset indent 389mount -t cd9660 -o -e /dev/cd0 /cdrom 390.Ed 391.Pp 392causes 393.Nm 394to execute the equivalent of: 395.Bd -literal -offset indent 396/sbin/mount_cd9660 -e /dev/cd0 /cdrom 397.Ed 398.Pp 399Options that take a value are specified using the -option=value syntax: 400.Bd -literal -offset indent 401mount -t msdosfs -o -u=fred,-g=wheel /dev/da0s1 /mnt 402.Ed 403.Pp 404is equivalent to 405.Bd -literal -offset indent 406/sbin/mount_msdosfs -u fred -g wheel /dev/da0s1 /mnt 407.Ed 408.Pp 409Additional options specific to file system types 410which are not internally known 411(see the description of the 412.Fl t 413option below) 414may be described in the manual pages for the associated 415.Pa /sbin/mount_ Ns Sy XXX 416utilities. 417.It Fl p 418Print mount information in 419.Xr fstab 5 420format. 421Implies also the 422.Fl v 423option. 424.It Fl r 425The file system is to be mounted read-only. 426Mount the file system read-only (even the super-user may not write it). 427The same as the 428.Cm ro 429argument to the 430.Fl o 431option. 432.It Fl t Oo Cm no Oc Ns Cm Ar type Ns Op Cm , Ns Ar type ... 433The argument following the 434.Fl t 435is used to indicate the file system type. 436The type 437.Cm ufs 438is the default. 439The 440.Fl t 441option can be used 442to indicate that the actions should only be taken on 443file systems of the specified type. 444More than one type may be specified in a comma separated list. 445The list of file system types can be prefixed with 446.Cm no 447to specify the file system types for which action should 448.Em not 449be taken. 450For example, the 451.Nm 452command: 453.Bd -literal -offset indent 454mount -a -t nonfs,nullfs 455.Ed 456.Pp 457mounts all file systems except those of type NFS and NULLFS. 458.Pp 459The default behavior of 460.Nm 461is to pass the 462.Fl t 463option directly to the 464.Xr nmount 2 465system call in the 466.Li fstype 467option. 468.Pp 469However, for the following file system types: 470.Cm cd9660 , 471.Cm mfs , 472.Cm msdosfs , 473.Cm nfs , 474.Cm nullfs , 475.Cm smbfs , 476.Cm udf , 477and 478.Cm unionfs 479.Nm 480will not call 481.Xr nmount 2 482directly and will instead attempt to execute a program in 483.Pa /sbin/mount_ Ns Ar type 484where 485.Ar type 486is replaced by the file system type name. 487For example, 488.Cm nfs 489file systems are mounted by the program 490.Pa /sbin/mount_nfs . 491.Pp 492Most file systems will be dynamically loaded by the kernel 493if not already present, and if the kernel module is available. 494.It Fl u 495The 496.Fl u 497flag indicates that the status of an already mounted file 498system should be changed. 499Any of the options discussed above (the 500.Fl o 501option) 502may be changed; 503also a file system can be changed from read-only to read-write 504or vice versa. 505An attempt to change from read-write to read-only will fail if any 506files on the file system are currently open for writing unless the 507.Fl f 508flag is also specified. 509The set of options is determined by applying the options specified 510in the argument to 511.Fl o 512and finally applying the 513.Fl r 514or 515.Fl w 516option. 517.It Fl v 518Verbose mode. 519If the 520.Fl v 521is used alone, show all file systems, including those that were mounted with the 522.Dv MNT_IGNORE 523flag and show additional information about each file system (including fsid 524when run by root). 525.It Fl w 526The file system object is to be read and write. 527.El 528.Sh ENVIRONMENT 529.Bl -tag -width ".Ev PATH_FSTAB" 530.It Ev PATH_FSTAB 531If the environment variable 532.Ev PATH_FSTAB 533is set, all operations are performed against the specified file. 534.Ev PATH_FSTAB 535will not be honored if the process environment or memory address space is 536considered 537.Dq tainted . 538(See 539.Xr issetugid 2 540for more information.) 541.El 542.Sh FILES 543.Bl -tag -width /etc/fstab -compact 544.It Pa /etc/fstab 545file system table 546.El 547.Sh DIAGNOSTICS 548Various, most of them are self-explanatory. 549.Pp 550.Dl XXXXX file system is not available 551.Pp 552The kernel does not support the respective file system type. 553Note that 554support for a particular file system might be provided either on a static 555(kernel compile-time), or dynamic basis (loaded as a kernel module by 556.Xr kldload 8 ) . 557.Sh SEE ALSO 558.Xr getfacl 1 , 559.Xr setfacl 1 , 560.Xr nmount 2 , 561.Xr acl 3 , 562.Xr getmntinfo 3 , 563.Xr libxo 3 , 564.Xr xo_parse_args 3 , 565.Xr mac 4 , 566.Xr cd9660 5 , 567.Xr devfs 5 , 568.Xr ext2fs 5 , 569.Xr fstab 5 , 570.Xr procfs 5 , 571.Xr tarfs 5 , 572.Xr tmpfs 5 , 573.Xr automount 8 , 574.Xr fstyp 8 , 575.Xr kldload 8 , 576.Xr mount_cd9660 8 , 577.Xr mount_msdosfs 8 , 578.Xr mount_nfs 8 , 579.Xr mount_nullfs 8 , 580.Xr mount_smbfs 8 , 581.Xr mount_udf 8 , 582.Xr mount_unionfs 8 , 583.Xr quotacheck 8 , 584.Xr umount 8 , 585.Xr zfs 8 , 586.Xr zpool 8 587.Sh HISTORY 588A 589.Nm 590utility appeared in 591.At v1 . 592.Sh CAVEATS 593After a successful 594.Nm , 595the permissions on the original mount point determine if 596.Pa ..\& 597is accessible from the mounted file system. 598The minimum permissions for 599the mount point for traversal across the mount point in both 600directions to be possible for all users is 0111 (execute for all). 601.Pp 602Use of the 603.Nm 604is preferred over the use of the file system specific 605.Pa mount_ Ns Sy XXX 606commands. 607In particular, 608.Xr mountd 8 609gets a 610.Dv SIGHUP 611signal (that causes an update of the export list) 612only when the file system is mounted via 613.Nm . 614.Sh BUGS 615It is possible for a corrupted file system to cause a crash. 616.Pp 617The 618.Fl p 619option will not list 620.Cm userquota 621or 622.Cm groupquota 623items from 624.Xr fstab 5 625because they are not true mount options and are not information returned by 626.Xr getmntinfo 3 . 627At boot 628.Xr quotacheck 8 , 629processes these items. 630