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1.1 ! root 1: % $Id: maps.tex,v 5.2 90/06/23 22:21:51 jsp Rel $ ! 2: % ! 3: % Copyright (c) 1989 Jan-Simon Pendry ! 4: % Copyright (c) 1989 Imperial College of Science, Technology & Medicine ! 5: % Copyright (c) 1989 The Regents of the University of California. ! 6: % All rights reserved. ! 7: % ! 8: % This code is derived from software contributed to Berkeley by ! 9: % Jan-Simon Pendry at Imperial College, London. ! 10: % ! 11: % Redistribution and use in source and binary forms are permitted provided ! 12: % that: (1) source distributions retain this entire copyright notice and ! 13: % comment, and (2) distributions including binaries display the following ! 14: % acknowledgement: ``This product includes software developed by the ! 15: % University of California, Berkeley and its contributors'' in the ! 16: % documentation or other materials provided with the distribution and in ! 17: % all advertising materials mentioning features or use of this software. ! 18: % Neither the name of the University nor the names of its contributors may ! 19: % be used to endorse or promote products derived from this software without ! 20: % specific prior written permission. ! 21: % THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED ! 22: % WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF ! 23: % MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. ! 24: % ! 25: % @(#)maps.tex 5.1 (Berkeley) 7/19/90 ! 26: ! 27: ! 28: \Chapter{Mount-maps} ! 29: ! 30: \Amd\ has no built-in knowledge of machines or filesystems. ! 31: External {\em mount-maps} are used to provide the required information. ! 32: Specifically, \amd\ needs to know when and under what conditions it should ! 33: mount filesystems. ! 34: ! 35: The map entry corresponding to the requested name contains ! 36: a list of possible locations from which to resolve the request. ! 37: Each location specifies filesystem type, information required by that ! 38: filesystem (for example the block special device in the case of \UFS), and ! 39: some information describing where to mount the filesystem (\see \Ref{mount location}). ! 40: A location may also contain {\em selectors} (\see \Ref{selectors}). ! 41: ! 42: \Section{Map Types} ! 43: ! 44: A mount-map can be implemented as a regular file, an ndbm database ! 45: a YP map \cite{sun:yp} or via ! 46: the {\em Hesiod} \cite{mit:hesiod} name ! 47: server. ! 48: In addition, the password ``file'' can be used as a source of ! 49: map information. ! 50: %\footnote{In future, gdbm databases will also be supported.} ! 51: A mount-map name is a sequence of characters. ! 52: When an automount point is created a handle on the mount-map ! 53: is obtained. If the the map name begins with the sequence ! 54: ``{\tt hesiod.}''\ then the {\em Hesiod} name server will be used. ! 55: If the map name is the string ``{\tt /etc/passwd}'' then the password ! 56: ``file'' will be used. ! 57: Otherwise the map name is referenced as a file, ! 58: then as an ndbm database by that name and then as a YP map. ! 59: As soon as a valid reference is found the map type is noted ! 60: for future use but any resources held are released, for example ! 61: any open file descriptors are closed. ! 62: The available map types are a configurable component of \amd\ and ! 63: can be displayed by running the command {\tt amd~-v}. ! 64: ! 65: By default, \amd\ does not cache any data retrieved from a mount map. ! 66: This is a policy decision based on the observation that most workstations ! 67: have more available CPU time than spare memory. ! 68: However, on a multi-user service or larger workstation the faster ! 69: response provided by a cache can be preferable. The \opt{cache} ! 70: option can be specified on automount points to alter the ! 71: caching behaviour (\see \Ref{auto-fs}). ! 72: Specifying {\tt cache:=mapdefault} selects a suitable default ! 73: cache mode depending on the map type. The individual defaults ! 74: are described below. ! 75: ! 76: \Subsection{File maps} ! 77: When \amd\ searches a file for a map entry it does a simple scan of the file ! 78: and supports both comments and continuation lines. ! 79: ! 80: Continuation lines are indicated by a backslash character (``{\verb+\+}'') as ! 81: the last character of a line in the file. The backslash, newline character ! 82: {\em and any leading white space on the following line} are discarded. A maximum ! 83: line length of 2047 characters is enforced after continuation lines are read ! 84: but before comments are stripped. Each line must end with ! 85: a newline character; that is newlines are terminators, not separators. ! 86: The following examples illustrate this: ! 87: \begin{verbatim} ! 88: key valA valB; \ ! 89: valC ! 90: \end{verbatim} ! 91: specifies {\em three} locations, and is identical to ! 92: \begin{verbatim} ! 93: key valA valB; valC ! 94: \end{verbatim} ! 95: However, ! 96: \begin{verbatim} ! 97: key valA valB;\ ! 98: valC ! 99: \end{verbatim} ! 100: specifies only {\em two} locations, and is identical to ! 101: \begin{verbatim} ! 102: key valA valB;valC ! 103: \end{verbatim} ! 104: ! 105: After a complete line has been read from the file, including continuations, ! 106: \amd\ determines whether there is a comment on the line. ! 107: A comment begins with a hash (``{\tt \#}'') character and continues to the ! 108: end of the line. ! 109: There is no way to escape or change the comment lead-in character. ! 110: ! 111: Note that continuation lines and comment support {\em only} apply to ! 112: file maps and ndbm maps built with the {\tt mk-amd-map} program. ! 113: ! 114: When caching is enabled, file maps have a default cache mode of {\tt all} (\see \Ref{afs:cache}). ! 115: ! 116: \Subsection{ndbm maps}\label{ndbm-maps} ! 117: An ndbm map may be used as a fast access form of a file map. ! 118: A program, {\tt mk-amd-map}, converts a normal map file into ! 119: an ndbm database. This program supports the same continuation and ! 120: comment conventions that are provided for file maps. ! 121: Note that ndbm format files {\em may not} be ! 122: sharable across machine architectures. ! 123: The notion of speed generally only applies to large maps; ! 124: a small map, less than a single disk block, is almost certainly ! 125: better implemented as a file map. ! 126: ! 127: ndbm maps do not support cache mode {\tt all} and, when ! 128: caching is enabled, have a default cache mode of {\tt inc} (\see \Ref{afs:cache}). ! 129: ! 130: \Subsection{NIS maps} ! 131: When using NIS (formerly YP), an \amd\ map is implemented directly by the ! 132: underlying NIS map. ! 133: Comments and continuation lines are {\em not} supported ! 134: in the automounter and must be stripped when constructing the NIS server's database. ! 135: ! 136: NIS maps do not support cache mode {\tt all} and, ! 137: when caching is enabled, ! 138: have a default cache mode of {\tt inc} (\see \Ref{afs:cache}). ! 139: ! 140: \Subsection{Hesiod} ! 141: When the map name begins with the string ``{\tt hesiod.}'' lookups ! 142: are made using the {\em Hesiod} name server. The string following ! 143: the dot is used as a name qualifier and is prepended with ! 144: the key being located. The entire string is then resolved in the ! 145: {\t automount} context. For example, if the map name is {\tt hesiod.homes} ! 146: and the key is {\tt jsp} then {\em Hesiod} is asked to resolve ! 147: {\tt jsp.homes.automount}. ! 148: ! 149: Hesiod maps do not support cache mode {\tt all} and, when ! 150: caching is enabled, have a default cache mode of {\tt inc} (\see \Ref{afs:cache}). ! 151: ! 152: \Subsection{Password}\label{map:passwd} ! 153: The password map support is unlike the four previous map types. ! 154: When the map name is the string {\tt /etc/passwd} ! 155: \amd\ can lookup a user name in the password file and re-arrange ! 156: the home directory field to produce a usable map entry. ! 157: ! 158: \Amd\ assumes the home directory has the format ! 159: {\tt /}{\em anydir}{\tt /}{\em dom$_1$}{\tt /../}{\em dom$_n$}{\tt /}{\em login}. ! 160: It breaks this string into a map entry where ! 161: \Var{rfs} has the value ``{\tt /}{\em anydir}{\tt /}{\em dom$_n$}'', ! 162: \Var{rhost} has the value ``{\em dom$_n$}{\tt .}{\em ...}{\tt .}{\em dom$_1$}'', ! 163: and \Var{sublink} has the value ``{\em login}''. ! 164: ! 165: Thus if the password file entry was ! 166: \begin{quote} ! 167: \tt /home/achilles/jsp ! 168: \end{quote} ! 169: the map ! 170: entry used by \amd\ would be ! 171: \begin{quote} ! 172: \tt rfs:=/home/achilles;rhost:=achilles;sublink:=jsp ! 173: \end{quote} ! 174: Similarly, if the password file entry was ! 175: \begin{quote} ! 176: \tt /home/cc/sugar/mjh ! 177: \end{quote} ! 178: the map entry used by \amd\ would be ! 179: \begin{quote} ! 180: \tt rfs:=/home/sugar;rhost:=sugar.cc;sublink:=jsp ! 181: \end{quote} ! 182: ! 183: %\Subsection{Gdbm} ! 184: ! 185: \Section{Key Lookup} ! 186: ! 187: The key is located in the map whose type was determined when the ! 188: automount point was first created. ! 189: In general the key is a pathname component. ! 190: In some circumstances this may be modified by variable expansion ! 191: (\see \Ref{var-expansion}) ! 192: and prefixing. ! 193: If the automount point has a prefix, specified by the \opt{pref} option, then ! 194: that is prepended to the search key before the map is searched. ! 195: ! 196: If the key cannot be found then a {\em wildcard} match is attempted. ! 197: Currently this simply attempts to locate a special key ``{\tt *}''. ! 198: If the wildcard is not found then an error code is propagated back to the ! 199: kernel, otherwise \amd\ proceeds as if an exact match had been found. ! 200: The value field is then used to resolve the mount request (\see \Ref{filesystems}). ! 201: ! 202: ! 203: \Section{Location Format}\label{opts:values} ! 204: ! 205: The value field from the lookup provides the information required to mount a filesystem. ! 206: The information is parsed according to the syntax shown in figure \ref{figure:so-grammar}. ! 207: \begin{figure}[htb] ! 208: \begin{tabbing} ! 209: Indent \= Long Gram Rule \= \kill ! 210: \> {\em location-list}:\\ ! 211: \> \> {\em location-selection}\\ ! 212: \> \> {\em location-list}\ \verb*+ +\ {\tt ||}\ \verb*+ +\ {\em location-selection}\\ ! 213: \> {\em location-selection}:\\ ! 214: \> \> {\em location}\\ ! 215: \> \> {\em location-selection}\ \verb*+ +\ {\em location}\\ ! 216: \> {\em location}:\\ ! 217: \> \> {\em location-info}\\ ! 218: \> \> {\tt -}{\em location-info}\\ ! 219: \> \> {\tt -}\\ ! 220: \> {\em location-info}:\\ ! 221: \> \> {\em sel-or-opt}\\ ! 222: \> \> {\em location-info}{\tt ;}{\em sel-or-opt}\\ ! 223: \> \> {\tt ;}\\ ! 224: \> {\em sel-or-opt}:\\ ! 225: \> \> {\em selection}\\ ! 226: \> \> {\em opt-ass}\\ ! 227: \> {\em selection}:\\ ! 228: \> \> {\rm selector}{\tt ==}{\em value}\\ ! 229: \> \> {\rm selector}{\tt !=}{\em value}\\ ! 230: \> {\em opt-ass}:\\ ! 231: \> \> {\rm option}{\tt :=}{\em value}\\ ! 232: \end{tabbing} ! 233: \caption{\label{figure:so-grammar}Location syntax} ! 234: \end{figure} ! 235: Note that unquoted whitespace is not allowed in a location description. ! 236: White space is only allowed, and is mandatory, where shown with the symbol \verb*+ +. ! 237: ! 238: A {\em location-selection} is a list of possible volumes with which to ! 239: satisfy the request. {\em location-selection}s are separated by the {\tt ||} ! 240: operator. The effect of this operator is to prevent use of location-selections ! 241: to its right if any of the location-selections on its left were selected ! 242: (see \Ref{selectors}). ! 243: ! 244: The location-selection, and singleton {\em location-list}, ! 245: {\tt type:=ufs;dev:=/dev/xd1g} would inform \amd\ to mount a ! 246: \UFS\ filesystem from the block special device {\tt /dev/xd1g}. ! 247: ! 248: The {\em sel-or-opt} component is either the name of an option required by a ! 249: specific filesystem, or it is the name of a built-in, predefined selector such ! 250: as the architecture type. ! 251: The value may be quoted with double quotes ``{\tt "}'', ! 252: for example {\tt type:="ufs";dev:="/dev/xd1g"}. These quotes are ! 253: stripped when the value is parsed and there is no way to get a double quote ! 254: into a value field. Double quotes are used to get white space into a value field, ! 255: which is needed for the program filesystem (\see \Ref{pfs}). ! 256: ! 257: \label{defaults}A location beginning with a dash ``{\tt -}'' is used ! 258: to specify default values for subsequent locations. ! 259: Any previously specified defaults in the location-list are discarded. The ! 260: default string can be empty in which case no defaults apply. ! 261: The location {\tt -fs:=/mnt;opts:=ro} would set the local mount point ! 262: to {\tt /mnt} and cause mounts to be read-only by default. ! 263: Defaults specified this way are appended to, and so ! 264: override, any global map defaults given ! 265: with {\tt /defaults}\label{/defaults}). ! 266: A {\tt /defaults} value {\em gdef} and a location list ! 267: \begin{quote} ! 268: ${\tt -}{\em def}_a\ $\verb*+ +$\ {\em loc}_{a_1}\ $\verb*+ +$\ {\em loc}_{a_2}\ $\verb*+ +$\ {\tt -}{\em def}_b\ $\verb*+ +$\ {\em loc}_{b_1}\ \ldots$ ! 269: \end{quote} ! 270: is equivalent to ! 271: \begin{quote} ! 272: ${\tt -}{\em gdef}{\tt ;}{\em def}_a\ $\verb*+ +$\ {\em loc}_{a_1}\ $\verb*+ +$\ {\em loc}_{a_2}\ $\verb*+ +$\ {\tt -}{\em gdef}{\tt ;}{\em def}_b\ $\verb*+ +$\ {\em loc}_{b_1}\ \ldots$ ! 273: \end{quote} ! 274: ! 275: \Subsection{Variable expansion}\label{var-expansion} ! 276: ! 277: To allow generic location specifications \amd\ does variable expansion ! 278: on each location and also on some of the option strings. ! 279: Any option or selector appearing in the form \Var{{\em var}} ! 280: is replaced by the current value of that option or selector. ! 281: For example, if the value of \Var{key} was {\tt bin}, \Var{autodir} was {\tt /a} ! 282: and \Var{fs} was \Var{autodir}{\tt /local/}\Var{key} then after ! 283: expansion \Var{fs} would have the value {\tt /a/local/bin}. ! 284: Any environment variable can be accessed in a similar way. ! 285: ! 286: Two pathname operators are available when expanding a variable. ! 287: If the variable name begins with ``{\tt /}'' then only the ! 288: last component of then pathname is substituted. For example, ! 289: if \Var{path} was {\tt /foo/bar} then \Var{/path} would be ! 290: expanded to {\tt bar}. ! 291: Similarly, if the variable name ends with ``{\tt /}'' then all but ! 292: the last component of the pathname is substituted. ! 293: In the previous example, \Var{path/} would be expanded to {\tt /foo}. ! 294: ! 295: Variable expansion is a two phase process. Before a location is parsed, all ! 296: references to selectors, \eg\ \Var{path}, are expanded. The location is then ! 297: parsed, selections are evaluated and option assignments recorded. If there ! 298: were no selections or they all succeeded the location is used and the values of ! 299: the following options are expanded in the order given: ! 300: \opt{sublink}, \opt{rfs}, \opt{fs}, \opt{opts}, \opt{mount} and \opt{unmount}. ! 301: Note that expansion of option values is done after {\em all} assignments have ! 302: been completed and not in a purely left to right order as is done by the shell. ! 303: This generally has the desired effect but care must be taken if one of the ! 304: options references another, in which case the ordering can become significant. ! 305: ! 306: There are two special cases concerning variable expansion. Firstly, before a map ! 307: is consulted, any selectors in the name received from the kernel are expanded. ! 308: For example, if the request from the kernel was for \Var{arch}{\tt .bin} and the ! 309: machine architecture was {\tt vax}, the value given to \Var{key} would be {\tt vax.bin}. ! 310: Secondly, the value of \Var{rhost} is expanded and normalized before the other options ! 311: are expanded. The normalization process strips any local sub-domain components. ! 312: For example, if \Var{domain} was {\tt Berkeley.EDU} and \Var{rhost} was initially ! 313: {\tt snow.Berkeley.EDU}, after the normalization it would simply be {\tt snow}. ! 314: ! 315: \Subsection{Selectors}\label{selectors} ! 316: ! 317: Selectors are used to control the use of a location. ! 318: It is possible to share a mount map between many machines in ! 319: such a way that filesystem location, architecture and operating ! 320: system differences are hidden from the users. ! 321: A selector of the form {\tt arch==sun3;os==sos4} would only apply ! 322: on Sun-3s running SunOS 4.$x$. ! 323: ! 324: Selectors are evaluated left to right. If a selector fails then that ! 325: location is ignored. Thus the selectors form a conjunction and the ! 326: locations form a disjunction. ! 327: If all the locations are ignored or otherwise fail then \amd\ uses ! 328: the {\em error} filesystem (\see \Ref{error-fs}). This is equivalent ! 329: to having a location {\tt type:=error} at the end of each mount-map ! 330: entry. ! 331: ! 332: The selectors currently implemented are: ! 333: ! 334: \begin{list}{}% ! 335: {\settowidth{\labelwidth}{{\tt autodir}}\setlength{\leftmargin}{1.2\labelwidth}} ! 336: \item[\tt arch\hfill] ! 337: the machine architecture which was automatically determined at compile time. ! 338: The architecture type can be displayed by running the command {\tt amd~-v}. ! 339: The currently supported architectures are listed in table \ref{table:arch}. ! 340: \begin{table}[htb] ! 341: \centering ! 342: \begin{tabular}{ll} ! 343: Name & Architecture \\ \hline ! 344: \tt alliant & Alliant FX/4 \\ ! 345: \tt arm & Acorn ARM \\ ! 346: \tt encore & Encore (reserved) \\ ! 347: \tt fps500 & FPS Model 500 \\ ! 348: \tt hp9000 & HP 9000/300 family \\ ! 349: \tt hp9k8 & HP 9000/800 family (reserved) \\ ! 350: \tt ibm032 & IBM RT \\ ! 351: \tt ibm6000 & IBM RISC System/6000 \\ ! 352: \tt macII & Apple Mac II \\ ! 353: \tt mips & MIPS R2000 \\ ! 354: \tt multimax & Encore Multimax \\ ! 355: \tt orion105 & HLH Orion 1/05 \\ ! 356: \tt powernode & Gould Powernode family \\ ! 357: \tt sun3 & Sun-3 family \\ ! 358: \tt sun4 & Sun-4 family \\ ! 359: \tt tahoe & Tahoe family \\ ! 360: \tt vax & DEC \sc Vax \\ ! 361: \end{tabular} ! 362: \caption{\label{table:arch}Architectures supported by \amd} ! 363: \end{table} ! 364: ! 365: \item[\tt autodir\hfill] ! 366: the default directory under which to mount filesystems. ! 367: This may be changed by the ``-a'' command line option. ! 368: See the \opt{fs} option. ! 369: ! 370: \item[\tt byte\hfill]\label{byte-selector} ! 371: the machine's byte ordering. This is either {\tt little}, indicating ! 372: little-endian, or {\tt big}, indicating big-endian. ! 373: One possible use is to share {\tt rwho} databases (see \Ref{example:rwho}). ! 374: Another is to share ndbm databases, ! 375: however this use can be considered a courageous juggling act. ! 376: ! 377: \item[\tt cluster\hfill] ! 378: is provided as a hook for the name of the local cluster. This can ! 379: be used to decide which servers to use for copies of replicated filesystems. ! 380: \Var{cluster} defaults to the value of \Var{domain} unless a different ! 381: value is set with the ``-C'' command line option. ! 382: ! 383: \item[\tt domain\hfill] ! 384: the local domain name as specified by the ``-d'' command line option. ! 385: See {\tt host}. ! 386: ! 387: \item[\tt host\hfill] ! 388: the local hostname as determined by {\bf gethostname}(2). ! 389: If no domain name was specified on the command line ! 390: and the hostname contains a period ``{\tt .}'' then the string ! 391: before the period is used as the host name, and the string ! 392: after the period is assigned to \Var{domain}. ! 393: For example, if the hostname is {\tt styx.doc.ic.ac.uk} the {\tt host} ! 394: would be {\tt styx} and {\tt domain} would be {\tt doc.ic.ac.uk}. ! 395: {\tt hostd} would be {\tt styx.doc.ic.ac.uk}. ! 396: ! 397: \item[\tt hostd\hfill] ! 398: is \Var{host} and \Var{domain} concatenated with a ``{\tt .}'' inserted between them ! 399: if required. ! 400: If \Var{domain} is an empty string then \Var{host} and \Var{hostd} will ! 401: be identical. ! 402: ! 403: \item[\tt karch\hfill] ! 404: is provided as a hook for the kernel architecture. This is used ! 405: on SunOS 4, for example, to distinguish between different {\tt /usr/kvm} volumes. ! 406: \Var{karch} defaults to the value of \Var{arch} unless a different ! 407: value is set with the ``-k'' command line option. ! 408: ! 409: \item[\tt os\hfill] ! 410: the operating system. ! 411: Like the machine architecture, this is automatically determined at compile time. ! 412: The operating system name can be displayed by running the command {\tt amd~-v}. ! 413: The currently supported operating systems are listed in table \ref{table:os}. ! 414: \begin{table}[htb] ! 415: \centering ! 416: \begin{tabular}{ll} ! 417: Name & System \\ \hline ! 418: \tt acis43 & 4.3 BSD for IBM RT \\ ! 419: \tt aix3 & AIX 3.1 \\ ! 420: \tt aux & System V for Mac-II \\ ! 421: \tt bsd44 & 4.4 BSD \\ ! 422: \tt concentrix & Concentrix 5.0 \\ ! 423: \tt fpx4 & Celerity FPX 4.1/2 \\ ! 424: \tt hlh42 & HLH OTS 1.$x$ (4.2 BSD) \\ ! 425: \tt hpux & HP-UX 6.$x$ \\ ! 426: \tt riscix & Acorn RISC iX \\ ! 427: \tt sos3 & SunOS 3.4 \& 3.5 \\ ! 428: \tt sos4 & SunOS 4.$x$ \\ ! 429: \tt umax43 & Umax 4.3 BSD \\ ! 430: \tt u2\_2 & Ultrix 2.2 \\ ! 431: \tt u3\_0 & Ultrix 3.0 \\ ! 432: \tt utx32 & Gould UTX/32 Rel 2.$x$ \\ ! 433: \tt xinu43 & mt Xinu MORE/bsd \\ ! 434: \end{tabular} ! 435: \caption{\label{table:os}Operating systems supported by \amd} ! 436: \end{table} ! 437: \end{list} ! 438: ! 439: The following selectors are also provided. Unlike the other selectors, ! 440: they vary for each lookup. ! 441: Note that when the name from the kernel is expanded prior to a map ! 442: lookup, these selectors are all defined as empty strings. ! 443: \begin{list}{}% ! 444: {\settowidth{\labelwidth}{{\tt autodir}}\setlength{\leftmargin}{1.2\labelwidth}} ! 445: \item[\tt key\hfill] ! 446: the name being resolved. ! 447: For example, if {\tt /home} is an automount point, then accessing ! 448: {\tt /home/foo}\label{foo-path} would set \Var{key} to the string {\tt foo}. ! 449: The key is prefixed by the \opt{pref} option set in the parent mount point. ! 450: The default prefix is an empty string. If the prefix was {\tt blah/} then ! 451: \Var{key} would be set to {\tt blah/foo}. ! 452: ! 453: \item[\tt map\hfill] ! 454: the name of the mount map being used. ! 455: ! 456: \item[\tt path\hfill] ! 457: the full pathname of the name being resolved. For example {\tt /home/foo} ! 458: in the example above. ! 459: ! 460: \end{list} ! 461: ! 462: Selectors can be negated by using {\tt !=} instead of {\tt ==}. ! 463: For example to select a location ! 464: on all non-{\sc Vax} machines the selector {\tt arch!=vax} would be used. ! 465: ! 466: \Subsection{Options}\label{options} ! 467: ! 468: Options are parsed concurrently with selectors. The difference is that ! 469: when an option is seen the string following the ``{\tt :=}'' is recorded for ! 470: later use. As a minimum the \opt{type} option must be specified. ! 471: Each filesystem type has other options which must also be specified. ! 472: The filesystem specific options are detailed in \Ref{filesystems}. ! 473: ! 474: The following options apply to more than one filesystem type: ! 475: \begin{list}{} ! 476: {\settowidth{\labelwidth}{{\tt sublink}}\setlength{\leftmargin}{1.2\labelwidth}} ! 477: \item[\tt delay\hfill] ! 478: the delay, in seconds, before an attempt will be made to mount from the current location. ! 479: Auxilliary data, such as network address, file handles and so on are computed ! 480: regardless of this value. ! 481: A delay can be used to implement the notion of primary and secondary file servers. ! 482: The secondary servers would have a delay of a few seconds, ! 483: thus giving the primary servers a chance to respond first. ! 484: ! 485: \item[\tt fs\hfill]\label{mount location} ! 486: the local mount point. ! 487: The semantics of this option vary between filesystems. ! 488: ! 489: For \NFS\ and \UFS\ filesystems the value of \Var{fs} is used as the local ! 490: mount point. It is important that this string uniquely identifies the ! 491: filesystem being mounted. To satisfy this requirement, it should contain the ! 492: name of the host on which the filesystem is resident and the pathname ! 493: of the filesystem on the local or remote host. ! 494: ! 495: The reason for ! 496: requiring the hostname is clear if replicated filesystems are considered. ! 497: If a fileserver goes down and a replacement filesystem is mounted then the {\em local} ! 498: mount point {\em must} be different from that of the filesystem which ! 499: is hung. ! 500: Some encoding of the filesystem name is required if more than one filesystem ! 501: is to be mounted from any given host. ! 502: ! 503: If the hostname is first in the path then all mounts from a particular ! 504: host will be gathered below a single directory. If that server goes ! 505: down then the hung mount points are less likely to be accidentally referenced, ! 506: for example when {\bf getwd}(3) traverses the namespace to find the pathname ! 507: of the current directory. ! 508: ! 509: The {\tt fs} defaults to \Var{autodir}/\Var{rhost}\Var{rfs}. ! 510: In addition, {\tt rhost} defaults to the local host name (\Var{host}) and ! 511: {\tt rfs} defaults to the value of \Var{path}, which ! 512: is the full path of the requested file; {\tt /home/foo} ! 513: in the example above (\see \Ref{foo-path}). ! 514: \Var{autodir} defaults to {\tt /a} but may be changed with the ``-a'' ! 515: command line option\footnote{Sun's automounter defaults to {\tt /tmp\_mnt}}. ! 516: Note that there is no ``{\tt /}'' between the \Var{rhost} and \Var{rfs} since ! 517: \Var{rfs} begins with a ``{\tt /}''. ! 518: ! 519: \item[\tt opts\hfill] ! 520: the options to pass to the mount system call. ! 521: A leading ``{\tt -}'' is silently ignored. ! 522: The mount options supported generally correspond to ! 523: those used by {\bf mount}(8) and are listed in table \ref{table:mount opts}. ! 524: Some additional pseudo-options are interpreted by \amd\ and ! 525: are listed in table \ref{table:pseudo-mount opts}. ! 526: Unless specifically overridden, each of the system default mount ! 527: options applies. ! 528: Any options not recognised are ignored. ! 529: If no options list is supplied the string {\tt rw,defaults} is used ! 530: and all the system default mount options apply. ! 531: \begin{table}[htb] ! 532: \centering ! 533: \begin{tabular}{lp{4in}} ! 534: Option & Semantics \\\hline ! 535: \tt grpid & Use BSD directory group-id semantics. \\ ! 536: \tt intr & Allow keyboard interrupts on hard mounts. \\ ! 537: \tt nodevs & Don't allow local special devices on this filesystem. \\ ! 538: \tt nosuid & Don't allow set-uid or set-gid executables on this filesystem. \\ ! 539: \tt quota & Enable quota checking on this mount. \\ ! 540: \tt retrans=$n$ & The number of \NFS\ retransmits made before a user error is generated ! 541: by a {\tt soft} mounted filesystem, and before a ! 542: {\tt hard} mounted filesystem reports {\tt NFS server {\em yoyo} ! 543: not responding still trying}. \\ ! 544: \tt ro & Mount this filesystem readonly. \\ ! 545: \tt soft & Give up after {\em retrans} retransmissions. \\ ! 546: \tt tcp & Use TCP/IP instead of UDP/IP \\ ! 547: \tt timeo=$n$ & The \NFS\ timeout, in tenth-seconds, before a request is retransmitted. \\ ! 548: \end{tabular} ! 549: \caption{Mount options passed to the mount system call\label{table:mount opts}} ! 550: \end{table} ! 551: ! 552: \begin{table}[htb] ! 553: \centering ! 554: \begin{tabular}{lp{4in}} ! 555: Option & Semantics \\\hline ! 556: \tt notimeout & Configures the mount so that its time-to-live will ! 557: never expire. This is also the default for some ! 558: filesystem types. \\ ! 559: % ! 560: % Implementation broken: ! 561: \tt ping=$n$ & The interval, in seconds, between keep-alive pings. When four ! 562: consecutive pings have failed the mount point is ! 563: marked as hung. This interval defaults to 30 seconds. ! 564: If the ping interval is negative, no pings are sent and ! 565: the host is assumed to be always up. Pings are never sent ! 566: for a TCP mount. \\ ! 567: ! 568: \tt retry=$n$ & The number of times to retry the mount system call. \\ ! 569: \tt utimeout=$n$& The interval, in seconds, by which the mount's ! 570: time-to-live\label{opt:utimeout} ! 571: is extended after an unmount attempt has failed. ! 572: In fact the interval is extended before the unmount ! 573: is attempted to avoid thrashing. The default value ! 574: is 120 seconds (two minutes) or as set by the ``-w'' ! 575: command line option. \\ ! 576: \end{tabular} ! 577: \caption{Mount options interpreted by \amd\label{table:pseudo-mount opts}} ! 578: \end{table} ! 579: ! 580: \item[\tt sublink\hfill] ! 581: the subdirectory within the mounted filesystem to which the reference ! 582: should point. ! 583: This can be used to prevent duplicate mounts in cases where multiple ! 584: directories in the same mounted filesystem are used. ! 585: ! 586: \item[\tt type\hfill] ! 587: the filesystem type to be used. A full description of each ! 588: type is given in \Ref{filesystems}. ! 589: ! 590: \end{list} ! 591: ! 592: Superfluous option specifications are ignored and are not reported ! 593: as errors.
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