exports(4)
exports - list of NFS filesystems being exported
As shipped in IRIX 6.5.19. Last changed in IRIX 6.5.19.
NAME exports - list of NFS filesystems being exported SYNOPSIS /etc/exports DESCRIPTION The file /etc/exports describes the filesystems that are being exported to NFS clients. It is created by the system administrator using a text editor It is processed by exportfs(1M) at system startup and by the mount request daemon, mountd(1M), each time a mount request is received. exportfs should be re-executed after making changes to the file. The file consists of a list of filesystems, the netgroup(4) or machine names allowed to remote mount each filesystem and possibly a list of options. The filesystem names are left justified and followed by a list of names separated by white space. The names are looked up in /etc/netgroup and then in /etc/hosts. A hyphen indicates the start of the options list. Multiple options are separated by commas. The default options are rw,anon=nobody. ro Export the directory read-only. If not specified, the directory is exported read-write. rw=hostname[:hostname]... Export the directory read-mostly. Read-mostly means exported read-only to most machines, but read-write to those specified. If no hosts are specified, the directory is exported read-write to all. anon=uid If a request comes from a host for uid 0 (typically ``root'') or from a host using null authentication, use uid as the effective user ID. uid can be either a name or an integer user ID from /etc/passwd. The default value for this option is ``nobody'' (uid -2). Because uid 0 permits access to files regardless of permission and ownership, NFS servers change uid 0 to the anonymous uid by default. Use the root option to permit accesses from hosts using uid 0. Setting the value of uid to -1 disables accesses from unknown users or from root on hosts not included in the root option. root=hostname[:hostname]... Give root access only to the root (uid 0) users from a specified hostname. The default is for no hosts to be granted root access. access=client[:client]... Give mount access to each client listed. A client can either be a hostname, or a netgroup (see netgroup(4)). Each client in the list is first checked for in the /etc/netgroup database and then in the /etc/hosts database. The default value allows any machine to mount the given directory. nohide Allows a client who mounts this entry's parent filesystem to access files in this filesystem. This is ``off'' by default, preventing a client who mounts this entry's parent filesystem from accessing files in this filesystem. Clients who mount a filesystem containing a hidden filesystem access the directory on which the hidden child is mounted, not the child filesystem's root directory. Be aware that using this option introduces a violation of RFC 1094, RFC 1813, and the XNFS specification. Using this option may cause the server not to interoperate properly with non-IRIX clients, particularly Linux clients. wsync Causes all writes to this filesystem to be performed synchronously. With this option, the server waits until written data is safely stored on a magnetic disk or other non- volatile medium before sending a positive response to the client. Without this option, the server performs delayed writes (it responds positively to the client, then writes the data at its convenience or when a sync(2) is executed). Delaying writes provides a great performance boost, but also introduces the risk of losing data if the server crashes after the response but before the data is stored. Use the wsync option if this risk is unacceptable. 32bitclients Causes the server to mask off the high order 32 bits of directory cookies in NFS version 3 directory operations. This option may be required when clients run 32-bit operating systems that assume the entire cookie is contained in 32 bits and reject responses containing version 3 cookies with high bits on. IRIX 5.3 and Solaris 2.5 are examples of 32-bit operating systems with this behavior, which produces error messages like "Cannot decode response" on directory operations. XFS filesystems on the server can generate cookies with high bits on. Exporting filesystems with the 32bitclients option causes these bits to be masked and prevents error messages. fsid=id This allows the administrator to set the fsid value that will be returned in the fsid field of the attributes returned to the client. This number is arbitrary but must uniquely identify the exported file system. The purpose of this option is twofold. First it provides a mechanism by which FailSafe can assign unique identifiers to exported file systems which may be failed over. This identifier can be the same on all nodes of the cluster. Secondly, it provides a way for administrators to work around NFS clients written to interpret and in some cases place restrictions on the fsid value returned in the attributes. If this option is used for this second purpose, it should not be used in conjunction with the nohide option, and the option should be used for all exported file systems. It is important to note that this option only affects the fsid contained in the file attributes. File handles are constructed differently and do not use the fsid value in the file attributes. A filesystem name that is not followed by a name list is exported to everyone. A ``#'' anywhere in the file indicates a comment extending to the end of the line on which it appears. A backslash ``\'' at the end of a line permits splitting long lines into shorter ones. When splitting the options across multiple lines, the character immediately preceeding the backslash must be one of ``-'', ``='', ``:'', or ``,''. Also, no whitespace may follow the backslash nor proceed the first character of the next line. EXAMPLES /usr/local # export to the world /usr clients # export to my clients /usr2 bonnie clyde # export to only these machines /usr3 -anon=guest # map client root & anonymous to guest / -ro # export the root filesystem /usr -ro,nohide # export all local filesystems read-only /d/local/src \ -rw,anon=guest,root=bonnie # multi-line example Exporting all your machine's local filesystems requires enumerating all local mount points and using nohide for filesystem other than root: / -ro /usr -ro,nohide /d -ro,nohide NOTE The nohide and wsync options are specific to IRIX. FILES /etc/exports SEE ALSO exportfs(1M), mountd(1M), showmount(1M), netgroup(4), passwd(4). WARNINGS You cannot export a directory that is either a parent- or a sub-directory of one that is currently exported and within the same filesystem. It would be illegal, for example, to export both /usr and /usr/local if both directories resided in the same disk partition. While there is no hard-coded maximum length, extremely long export lists (hundreds of hosts or netgroups for a single exported directory) may cause mount requests for that exported directory to time out. In the Trusted IRIX environment filesystems should not be exported to non-Trusted clients. Trix clients should be explicitly defined when exporting (see examples).