src/Doc/System/Basics.thy
author wenzelm
Sat May 11 18:45:38 2013 +0200 (2013-05-11)
changeset 51932 f196352201d6
parent 51434 e19a22974c72
child 52052 892061142ba6
permissions -rw-r--r--
removed some obsolete PGIP/PGEclipse material;
     1 theory Basics
     2 imports Base
     3 begin
     4 
     5 chapter {* The Isabelle system environment *}
     6 
     7 text {* This manual describes Isabelle together with related tools and
     8   user interfaces as seen from a system oriented view.  See also the
     9   \emph{Isabelle/Isar Reference Manual}~\cite{isabelle-isar-ref} for
    10   the actual Isabelle input language and related concepts, and
    11   \emph{The Isabelle/Isar Implementation
    12   Manual}~\cite{isabelle-implementation} for the main concepts of the
    13   underlying implementation in Isabelle/ML.
    14 
    15   \medskip The Isabelle system environment provides the following
    16   basic infrastructure to integrate tools smoothly.
    17 
    18   \begin{enumerate}
    19 
    20   \item The \emph{Isabelle settings} mechanism provides process
    21   environment variables to all Isabelle executables (including tools
    22   and user interfaces).
    23 
    24   \item The raw \emph{Isabelle process} (@{executable_ref
    25   "isabelle-process"}) runs logic sessions either interactively or in
    26   batch mode.  In particular, this view abstracts over the invocation
    27   of the actual ML system to be used.  Regular users rarely need to
    28   care about the low-level process.
    29 
    30   \item The main \emph{Isabelle tool wrapper} (@{executable_ref
    31   isabelle}) provides a generic startup environment Isabelle related
    32   utilities, user interfaces etc.  Such tools automatically benefit
    33   from the settings mechanism.
    34 
    35   \end{enumerate}
    36 *}
    37 
    38 
    39 section {* Isabelle settings \label{sec:settings} *}
    40 
    41 text {*
    42   The Isabelle system heavily depends on the \emph{settings
    43   mechanism}\indexbold{settings}.  Essentially, this is a statically
    44   scoped collection of environment variables, such as @{setting
    45   ISABELLE_HOME}, @{setting ML_SYSTEM}, @{setting ML_HOME}.  These
    46   variables are \emph{not} intended to be set directly from the shell,
    47   though.  Isabelle employs a somewhat more sophisticated scheme of
    48   \emph{settings files} --- one for site-wide defaults, another for
    49   additional user-specific modifications.  With all configuration
    50   variables in clearly defined places, this scheme is more
    51   maintainable and user-friendly than global shell environment
    52   variables.
    53 
    54   In particular, we avoid the typical situation where prospective
    55   users of a software package are told to put several things into
    56   their shell startup scripts, before being able to actually run the
    57   program. Isabelle requires none such administrative chores of its
    58   end-users --- the executables can be invoked straight away.
    59   Occasionally, users would still want to put the @{file
    60   "$ISABELLE_HOME/bin"} directory into their shell's search path, but
    61   this is not required.
    62 *}
    63 
    64 
    65 subsection {* Bootstrapping the environment \label{sec:boot} *}
    66 
    67 text {* Isabelle executables need to be run within a proper settings
    68   environment.  This is bootstrapped as described below, on the first
    69   invocation of one of the outer wrapper scripts (such as
    70   @{executable_ref isabelle}).  This happens only once for each
    71   process tree, i.e.\ the environment is passed to subprocesses
    72   according to regular Unix conventions.
    73 
    74   \begin{enumerate}
    75 
    76   \item The special variable @{setting_def ISABELLE_HOME} is
    77   determined automatically from the location of the binary that has
    78   been run.
    79   
    80   You should not try to set @{setting ISABELLE_HOME} manually. Also
    81   note that the Isabelle executables either have to be run from their
    82   original location in the distribution directory, or via the
    83   executable objects created by the @{tool install} tool.  Symbolic
    84   links are admissible, but a plain copy of the @{file
    85   "$ISABELLE_HOME/bin"} files will not work!
    86 
    87   \item The file @{file "$ISABELLE_HOME/etc/settings"} is run as a
    88   @{executable_ref bash} shell script with the auto-export option for
    89   variables enabled.
    90   
    91   This file holds a rather long list of shell variable assigments,
    92   thus providing the site-wide default settings.  The Isabelle
    93   distribution already contains a global settings file with sensible
    94   defaults for most variables.  When installing the system, only a few
    95   of these may have to be adapted (probably @{setting ML_SYSTEM}
    96   etc.).
    97   
    98   \item The file @{verbatim "$ISABELLE_HOME_USER/etc/settings"} (if it
    99   exists) is run in the same way as the site default settings. Note
   100   that the variable @{setting ISABELLE_HOME_USER} has already been set
   101   before --- usually to something like @{verbatim
   102   "$USER_HOME/.isabelle/IsabelleXXXX"}.
   103   
   104   Thus individual users may override the site-wide defaults.  See also
   105   file @{file "$ISABELLE_HOME/etc/user-settings.sample"} in the
   106   distribution.  Typically, a user settings file would contain only a
   107   few lines, just the assigments that are really changed.  One should
   108   definitely \emph{not} start with a full copy the basic @{file
   109   "$ISABELLE_HOME/etc/settings"}. This could cause very annoying
   110   maintainance problems later, when the Isabelle installation is
   111   updated or changed otherwise.
   112   
   113   \end{enumerate}
   114 
   115   Since settings files are regular GNU @{executable_def bash} scripts,
   116   one may use complex shell commands, such as @{verbatim "if"} or
   117   @{verbatim "case"} statements to set variables depending on the
   118   system architecture or other environment variables.  Such advanced
   119   features should be added only with great care, though. In
   120   particular, external environment references should be kept at a
   121   minimum.
   122 
   123   \medskip A few variables are somewhat special:
   124 
   125   \begin{itemize}
   126 
   127   \item @{setting_def ISABELLE_PROCESS} and @{setting_def ISABELLE_TOOL} are set
   128   automatically to the absolute path names of the @{executable
   129   "isabelle-process"} and @{executable isabelle} executables,
   130   respectively.
   131   
   132   \item @{setting_ref ISABELLE_OUTPUT} will have the identifiers of
   133   the Isabelle distribution (cf.\ @{setting ISABELLE_IDENTIFIER}) and
   134   the ML system (cf.\ @{setting ML_IDENTIFIER}) appended automatically
   135   to its value.
   136 
   137   \end{itemize}
   138 
   139   \medskip Note that the settings environment may be inspected with
   140   the @{tool getenv} tool.  This might help to figure out the effect
   141   of complex settings scripts.  *}
   142 
   143 
   144 subsection {* Common variables *}
   145 
   146 text {*
   147   This is a reference of common Isabelle settings variables. Note that
   148   the list is somewhat open-ended. Third-party utilities or interfaces
   149   may add their own selection. Variables that are special in some
   150   sense are marked with @{text "\<^sup>*"}.
   151 
   152   \begin{description}
   153 
   154   \item[@{setting_def USER_HOME}@{text "\<^sup>*"}] Is the cross-platform
   155   user home directory.  On Unix systems this is usually the same as
   156   @{setting HOME}, but on Windows it is the regular home directory of
   157   the user, not the one of within the Cygwin root
   158   file-system.\footnote{Cygwin itself offers another choice whether
   159   its HOME should point to the \texttt{/home} directory tree or the
   160   Windows user home.}
   161 
   162  \item[@{setting_def ISABELLE_HOME}@{text "\<^sup>*"}] is the location of the
   163   top-level Isabelle distribution directory. This is automatically
   164   determined from the Isabelle executable that has been invoked.  Do
   165   not attempt to set @{setting ISABELLE_HOME} yourself from the shell!
   166   
   167   \item[@{setting_def ISABELLE_HOME_USER}] is the user-specific
   168   counterpart of @{setting ISABELLE_HOME}. The default value is
   169   relative to @{verbatim "$USER_HOME/.isabelle"}, under rare
   170   circumstances this may be changed in the global setting file.
   171   Typically, the @{setting ISABELLE_HOME_USER} directory mimics
   172   @{setting ISABELLE_HOME} to some extend. In particular, site-wide
   173   defaults may be overridden by a private @{verbatim
   174   "$ISABELLE_HOME_USER/etc/settings"}.
   175 
   176   \item[@{setting_def ISABELLE_PLATFORM_FAMILY}@{text "\<^sup>*"}] is
   177   automatically set to the general platform family: @{verbatim linux},
   178   @{verbatim macos}, @{verbatim windows}.  Note that
   179   platform-dependent tools usually need to refer to the more specific
   180   identification according to @{setting ISABELLE_PLATFORM}, @{setting
   181   ISABELLE_PLATFORM32}, @{setting ISABELLE_PLATFORM64}.
   182 
   183   \item[@{setting_def ISABELLE_PLATFORM}@{text "\<^sup>*"}] is automatically
   184   set to a symbolic identifier for the underlying hardware and
   185   operating system.  The Isabelle platform identification always
   186   refers to the 32 bit variant, even this is a 64 bit machine.  Note
   187   that the ML or Java runtime may have a different idea, depending on
   188   which binaries are actually run.
   189 
   190   \item[@{setting_def ISABELLE_PLATFORM64}@{text "\<^sup>*"}] is similar to
   191   @{setting ISABELLE_PLATFORM} but refers to the proper 64 bit variant
   192   on a platform that supports this; the value is empty for 32 bit.
   193   Note that the following bash expression (including the quotes)
   194   prefers the 64 bit platform, if that is available:
   195 
   196   @{verbatim [display] "\"${ISABELLE_PLATFORM64:-$ISABELLE_PLATFORM}\""}
   197 
   198   \item[@{setting_def ISABELLE_PROCESS}@{text "\<^sup>*"}, @{setting
   199   ISABELLE_TOOL}@{text "\<^sup>*"}] are automatically set to the full path
   200   names of the @{executable "isabelle-process"} and @{executable
   201   isabelle} executables, respectively.  Thus other tools and scripts
   202   need not assume that the @{file "$ISABELLE_HOME/bin"} directory is
   203   on the current search path of the shell.
   204   
   205   \item[@{setting_def ISABELLE_IDENTIFIER}@{text "\<^sup>*"}] refers
   206   to the name of this Isabelle distribution, e.g.\ ``@{verbatim
   207   Isabelle2012}''.
   208 
   209   \item[@{setting_def ML_SYSTEM}, @{setting_def ML_HOME},
   210   @{setting_def ML_OPTIONS}, @{setting_def ML_PLATFORM}, @{setting_def
   211   ML_IDENTIFIER}@{text "\<^sup>*"}] specify the underlying ML system
   212   to be used for Isabelle.  There is only a fixed set of admissable
   213   @{setting ML_SYSTEM} names (see the @{file
   214   "$ISABELLE_HOME/etc/settings"} file of the distribution).
   215   
   216   The actual compiler binary will be run from the directory @{setting
   217   ML_HOME}, with @{setting ML_OPTIONS} as first arguments on the
   218   command line.  The optional @{setting ML_PLATFORM} may specify the
   219   binary format of ML heap images, which is useful for cross-platform
   220   installations.  The value of @{setting ML_IDENTIFIER} is
   221   automatically obtained by composing the values of @{setting
   222   ML_SYSTEM}, @{setting ML_PLATFORM} and the Isabelle version values.
   223 
   224   \item[@{setting_def ISABELLE_POLYML}@{text "\<^sup>*"}] is @{verbatim true}
   225   for @{setting ML_SYSTEM} values derived from Poly/ML, as opposed to
   226   SML/NJ where it is empty.  This is particularly useful with the
   227   build option @{system_option condition}
   228   (\secref{sec:system-options}) to restrict big sessions to something
   229   that SML/NJ can still handle.
   230 
   231   \item[@{setting_def ISABELLE_JDK_HOME}] needs to point to a full JDK
   232   (Java Development Kit) installation with @{verbatim javac} and
   233   @{verbatim jar} executables.  This is essential for Isabelle/Scala
   234   and other JVM-based tools to work properly.  Note that conventional
   235   @{verbatim JAVA_HOME} usually points to the JRE (Java Runtime
   236   Environment), not JDK.
   237   
   238   \item[@{setting_def ISABELLE_PATH}] is a list of directories
   239   (separated by colons) where Isabelle logic images may reside.  When
   240   looking up heaps files, the value of @{setting ML_IDENTIFIER} is
   241   appended to each component internally.
   242   
   243   \item[@{setting_def ISABELLE_OUTPUT}@{text "\<^sup>*"}] is a
   244   directory where output heap files should be stored by default. The
   245   ML system and Isabelle version identifier is appended here, too.
   246   
   247   \item[@{setting_def ISABELLE_BROWSER_INFO}] is the directory where
   248   theory browser information (HTML text, graph data, and printable
   249   documents) is stored (see also \secref{sec:info}).  The default
   250   value is @{verbatim "$ISABELLE_HOME_USER/browser_info"}.
   251   
   252   \item[@{setting_def ISABELLE_LOGIC}] specifies the default logic to
   253   load if none is given explicitely by the user.  The default value is
   254   @{verbatim HOL}.
   255   
   256   \item[@{setting_def ISABELLE_LINE_EDITOR}] specifies the default
   257   line editor for the @{tool_ref tty} interface.
   258 
   259   \item[@{setting_def ISABELLE_USEDIR_OPTIONS}] is implicitly prefixed
   260   to the command line of any @{tool_ref usedir} invocation. This
   261   typically contains compilation options for object-logics --- @{tool
   262   usedir} is the basic tool for managing logic sessions (cf.\ the
   263   @{verbatim IsaMakefile}s in the distribution).
   264 
   265   \item[@{setting_def ISABELLE_LATEX}, @{setting_def
   266   ISABELLE_PDFLATEX}, @{setting_def ISABELLE_BIBTEX}, @{setting_def
   267   ISABELLE_DVIPS}] refer to {\LaTeX} related tools for Isabelle
   268   document preparation (see also \secref{sec:tool-latex}).
   269   
   270   \item[@{setting_def ISABELLE_TOOLS}] is a colon separated list of
   271   directories that are scanned by @{executable isabelle} for external
   272   utility programs (see also \secref{sec:isabelle-tool}).
   273   
   274   \item[@{setting_def ISABELLE_DOCS}] is a colon separated list of
   275   directories with documentation files.
   276   
   277   \item[@{setting_def ISABELLE_DOC_FORMAT}] specifies the preferred
   278   document format, typically @{verbatim pdf} or @{verbatim dvi}.
   279 
   280   \item[@{setting_def PDF_VIEWER}] specifies the command-line to be
   281   used for displaying @{verbatim pdf} files.
   282 
   283   \item[@{setting_def DVI_VIEWER}] specifies the command-line to be
   284   used for displaying @{verbatim dvi} files.
   285   
   286   \item[@{setting_def PRINT_COMMAND}] specifies the standard printer
   287   spool command, which is expected to accept @{verbatim ps} files.
   288   
   289   \item[@{setting_def ISABELLE_TMP_PREFIX}@{text "\<^sup>*"}] is the
   290   prefix from which any running @{executable "isabelle-process"}
   291   derives an individual directory for temporary files.  The default is
   292   somewhere in @{verbatim "/tmp"}.
   293   
   294   \end{description}
   295 *}
   296 
   297 
   298 subsection {* Additional components \label{sec:components} *}
   299 
   300 text {* Any directory may be registered as an explicit \emph{Isabelle
   301   component}.  The general layout conventions are that of the main
   302   Isabelle distribution itself, and the following two files (both
   303   optional) have a special meaning:
   304 
   305   \begin{itemize}
   306 
   307   \item @{verbatim "etc/settings"} holds additional settings that are
   308   initialized when bootstrapping the overall Isabelle environment,
   309   cf.\ \secref{sec:boot}.  As usual, the content is interpreted as a
   310   @{verbatim bash} script.  It may refer to the component's enclosing
   311   directory via the @{verbatim "COMPONENT"} shell variable.
   312 
   313   For example, the following setting allows to refer to files within
   314   the component later on, without having to hardwire absolute paths:
   315 
   316 \begin{ttbox}
   317 MY_COMPONENT_HOME="$COMPONENT"
   318 \end{ttbox}
   319 
   320   Components can also add to existing Isabelle settings such as
   321   @{setting_def ISABELLE_TOOLS}, in order to provide
   322   component-specific tools that can be invoked by end-users.  For
   323   example:
   324 
   325 \begin{ttbox}
   326 ISABELLE_TOOLS="$ISABELLE_TOOLS:$COMPONENT/lib/Tools"
   327 \end{ttbox}
   328 
   329   \item @{verbatim "etc/components"} holds a list of further
   330   sub-components of the same structure.  The directory specifications
   331   given here can be either absolute (with leading @{verbatim "/"}) or
   332   relative to the component's main directory.
   333 
   334   \end{itemize}
   335 
   336   The root of component initialization is @{setting ISABELLE_HOME}
   337   itself.  After initializing all of its sub-components recursively,
   338   @{setting ISABELLE_HOME_USER} is included in the same manner (if
   339   that directory exists).  This allows to install private components
   340   via @{verbatim "$ISABELLE_HOME_USER/etc/components"}, although it is
   341   often more convenient to do that programmatically via the
   342   \verb,init_component, shell function in the \verb,etc/settings,
   343   script of \verb,$ISABELLE_HOME_USER, (or any other component
   344   directory).  For example:
   345 \begin{ttbox}
   346 init_component "$HOME/screwdriver-2.0"
   347 \end{ttbox}
   348 
   349   This is tolerant wrt.\ missing component directories, but might
   350   produce a warning.
   351 
   352   \medskip More complex situations may be addressed by initializing
   353   components listed in a given catalog file, relatively to some base
   354   directory:
   355 
   356 \begin{ttbox}
   357 init_components "$HOME/my_component_store" "some_catalog_file"
   358 \end{ttbox}
   359 
   360   The component directories listed in the catalog file are treated as
   361   relative to the given base directory.
   362 
   363   See also \secref{sec:tool-components} for some tool-support for
   364   resolving components that are formally initialized but not installed
   365   yet.
   366 *}
   367 
   368 
   369 section {* The raw Isabelle process *}
   370 
   371 text {*
   372   The @{executable_def "isabelle-process"} executable runs bare-bones
   373   Isabelle logic sessions --- either interactively or in batch mode.
   374   It provides an abstraction over the underlying ML system, and over
   375   the actual heap file locations.  Its usage is:
   376 
   377 \begin{ttbox}
   378 Usage: isabelle-process [OPTIONS] [INPUT] [OUTPUT]
   379 
   380   Options are:
   381     -I           startup Isar interaction mode
   382     -P           startup Proof General interaction mode
   383     -S           secure mode -- disallow critical operations
   384     -T ADDR      startup process wrapper, with socket address
   385     -W IN:OUT    startup process wrapper, with input/output fifos
   386     -e MLTEXT    pass MLTEXT to the ML session
   387     -f           pass 'Session.finish();' to the ML session
   388     -m MODE      add print mode for output
   389     -q           non-interactive session
   390     -r           open heap file read-only
   391     -u           pass 'use"ROOT.ML";' to the ML session
   392     -w           reset write permissions on OUTPUT
   393 
   394   INPUT (default "\$ISABELLE_LOGIC") and OUTPUT specify in/out heaps.
   395   These are either names to be searched in the Isabelle path, or
   396   actual file names (containing at least one /).
   397   If INPUT is "RAW_ML_SYSTEM", just start the bare bones ML system.
   398 \end{ttbox}
   399 
   400   Input files without path specifications are looked up in the
   401   @{setting ISABELLE_PATH} setting, which may consist of multiple
   402   components separated by colons --- these are tried in the given
   403   order with the value of @{setting ML_IDENTIFIER} appended
   404   internally.  In a similar way, base names are relative to the
   405   directory specified by @{setting ISABELLE_OUTPUT}.  In any case,
   406   actual file locations may also be given by including at least one
   407   slash (@{verbatim "/"}) in the name (hint: use @{verbatim "./"} to
   408   refer to the current directory).
   409 *}
   410 
   411 
   412 subsubsection {* Options *}
   413 
   414 text {*
   415   If the input heap file does not have write permission bits set, or
   416   the @{verbatim "-r"} option is given explicitely, then the session
   417   started will be read-only.  That is, the ML world cannot be
   418   committed back into the image file.  Otherwise, a writable session
   419   enables commits into either the input file, or into another output
   420   heap file (if that is given as the second argument on the command
   421   line).
   422 
   423   The read-write state of sessions is determined at startup only, it
   424   cannot be changed intermediately. Also note that heap images may
   425   require considerable amounts of disk space (approximately
   426   50--200~MB). Users are responsible for themselves to dispose their
   427   heap files when they are no longer needed.
   428 
   429   \medskip The @{verbatim "-w"} option makes the output heap file
   430   read-only after terminating.  Thus subsequent invocations cause the
   431   logic image to be read-only automatically.
   432 
   433   \medskip Using the @{verbatim "-e"} option, arbitrary ML code may be
   434   passed to the Isabelle session from the command line. Multiple
   435   @{verbatim "-e"}'s are evaluated in the given order. Strange things
   436   may happen when errorneous ML code is provided. Also make sure that
   437   the ML commands are terminated properly by semicolon.
   438 
   439   \medskip The @{verbatim "-u"} option is a shortcut for @{verbatim
   440   "-e"} passing ``@{verbatim "use \"ROOT.ML\";"}'' to the ML session.
   441   The @{verbatim "-f"} option passes ``@{verbatim
   442   "Session.finish();"}'', which is intended mainly for administrative
   443   purposes.
   444 
   445   \medskip The @{verbatim "-m"} option adds identifiers of print modes
   446   to be made active for this session. Typically, this is used by some
   447   user interface, e.g.\ to enable output of proper mathematical
   448   symbols.
   449 
   450   \medskip Isabelle normally enters an interactive top-level loop
   451   (after processing the @{verbatim "-e"} texts). The @{verbatim "-q"}
   452   option inhibits interaction, thus providing a pure batch mode
   453   facility.
   454 
   455   \medskip The @{verbatim "-I"} option makes Isabelle enter Isar
   456   interaction mode on startup, instead of the primitive ML top-level.
   457   The @{verbatim "-P"} option configures the top-level loop for
   458   interaction with the Proof General user interface.
   459 
   460   \medskip The @{verbatim "-T"} or @{verbatim "-W"} option makes
   461   Isabelle enter a special process wrapper for interaction via
   462   Isabelle/Scala, see also @{file
   463   "~~/src/Pure/System/isabelle_process.scala"}.  The protocol between
   464   the ML and JVM process is private to the implementation.
   465 
   466   \medskip The @{verbatim "-S"} option makes the Isabelle process more
   467   secure by disabling some critical operations, notably runtime
   468   compilation and evaluation of ML source code.
   469 *}
   470 
   471 
   472 subsubsection {* Examples *}
   473 
   474 text {*
   475   Run an interactive session of the default object-logic (as specified
   476   by the @{setting ISABELLE_LOGIC} setting) like this:
   477 \begin{ttbox}
   478 isabelle-process
   479 \end{ttbox}
   480 
   481   Usually @{setting ISABELLE_LOGIC} refers to one of the standard
   482   logic images, which are read-only by default.  A writable session
   483   --- based on @{verbatim HOL}, but output to @{verbatim Test} (in the
   484   directory specified by the @{setting ISABELLE_OUTPUT} setting) ---
   485   may be invoked as follows:
   486 \begin{ttbox}
   487 isabelle-process HOL Test
   488 \end{ttbox}
   489   Ending this session normally (e.g.\ by typing control-D) dumps the
   490   whole ML system state into @{verbatim Test} (be prepared for more
   491   than 100\,MB):
   492 
   493   The @{verbatim Test} session may be continued later (still in
   494   writable state) by:
   495 \begin{ttbox}
   496 isabelle-process Test
   497 \end{ttbox}
   498   A read-only @{verbatim Test} session may be started by:
   499 \begin{ttbox}
   500 isabelle-process -r Test
   501 \end{ttbox}
   502 
   503   \bigskip The next example demonstrates batch execution of Isabelle.
   504   We retrieve the @{verbatim Main} theory value from the theory loader
   505   within ML (observe the delicate quoting rules for the Bash shell
   506   vs.\ ML):
   507 \begin{ttbox}
   508 isabelle-process -e 'Thy_Info.get_theory "Main";' -q -r HOL
   509 \end{ttbox}
   510   Note that the output text will be interspersed with additional junk
   511   messages by the ML runtime environment.  The @{verbatim "-W"} option
   512   allows to communicate with the Isabelle process via an external
   513   program in a more robust fashion.
   514 *}
   515 
   516 
   517 section {* The Isabelle tool wrapper \label{sec:isabelle-tool} *}
   518 
   519 text {*
   520   All Isabelle related tools and interfaces are called via a common
   521   wrapper --- @{executable isabelle}:
   522 
   523 \begin{ttbox}
   524 Usage: isabelle TOOL [ARGS ...]
   525 
   526   Start Isabelle tool NAME with ARGS; pass "-?" for tool specific help.
   527 
   528 Available tools:
   529   \dots
   530 \end{ttbox}
   531 
   532   In principle, Isabelle tools are ordinary executable scripts that
   533   are run within the Isabelle settings environment, see
   534   \secref{sec:settings}.  The set of available tools is collected by
   535   @{executable isabelle} from the directories listed in the @{setting
   536   ISABELLE_TOOLS} setting.  Do not try to call the scripts directly
   537   from the shell.  Neither should you add the tool directories to your
   538   shell's search path!
   539 *}
   540 
   541 
   542 subsubsection {* Examples *}
   543 
   544 text {* Show the list of available documentation of the Isabelle
   545   distribution:
   546 
   547 \begin{ttbox}
   548   isabelle doc
   549 \end{ttbox}
   550 
   551   View a certain document as follows:
   552 \begin{ttbox}
   553   isabelle doc system
   554 \end{ttbox}
   555 
   556   Query the Isabelle settings environment:
   557 \begin{ttbox}
   558   isabelle getenv ISABELLE_HOME_USER
   559 \end{ttbox}
   560 *}
   561 
   562 end