2008-07-11 Atsushi Enomoto <atsushi@ximian.com>

[mono.git] / man / mono.1

.\" 
.\" mono manual page.
.\" (C) 2003 Ximian, Inc. 
.\" (C) 2004-2005 Novell, Inc. 
.\" Author:
.\"   Miguel de Icaza (miguel@gnu.org)
.\"
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.TH Mono "Mono 1.0"
.SH NAME
mono \- Mono's ECMA-CLI native code generator (Just-in-Time and Ahead-of-Time)
.SH SYNOPSIS
.PP
.B mono [options] file [arguments...]
.SH DESCRIPTION
\fImono\fP is a runtime implementation of the ECMA Common Language
Infrastructure.  This can be used to run ECMA and .NET applications.
.PP
The runtime contains a native code generator that transforms the
Common Intermediate Language into native code.
.PP
The code generator can operate in two modes: just in time compilation
(JIT) or ahead of time compilation (AOT).  Since code can be
dynamically loaded, the runtime environment and the JIT are always
present, even if code is compiled ahead of time.
.PP
The runtime loads the specified
.I file
and optionally passes
the
.I arguments
to it.  The 
.I file
is an ECMA assembly.  They typically have a .exe or .dll extension.
.PP
The runtime provides a number of configuration options for running
applications, for developing and debugging, and for testing and
debugging the runtime itself.
.SH PORTABILITY
On Unix-based systems, Mono provides a mechanism to emulate the 
Windows-style file access, this includes providing a case insensitive
view of the file system, directory separator mapping (from \\ to /) and
stripping the drive letters.
.PP
This functionality is enabled by setting the 
.B MONO_IOMAP 
environment variable to one of 
.B all, drive
and 
.B case.
.PP
See the description for 
.B MONO_IOMAP
in the environment variables section for more details.
.SH RUNTIME OPTIONS
The following options are available:
.TP
\fB--aot\fR, \fB--aot[=options]\fR
This option is used to precompile the CIL code in the specified
assembly to native code.  The generated code is stored in a file with
the extension .so.  This file will be automatically picked up by the
runtime when the assembly is executed.  
.Sp 
Ahead-of-Time compilation is most useful if you use it in combination
with the -O=all,-shared flag which enables all of the optimizations in
the code generator to be performed.  Some of those optimizations are
not practical for Just-in-Time compilation since they might be very
time consuming.
.Sp
Unlike the .NET Framework, Ahead-of-Time compilation will not generate
domain independent code: it generates the same code that the
Just-in-Time compiler would produce.   Since most applications use a
single domain, this is fine.   If you want to optimize the generated
code for use in multi-domain applications, consider using the
-O=shared flag.
.Sp
This pre-compiles the methods, but the original assembly is still
required to execute as this one contains the metadata and exception
information which is not available on the generated file.  When
precompiling code, you might want to compile with all optimizations
(-O=all).  Pre-compiled code is position independent code.
.Sp
Pre compilation is just a mechanism to reduce startup time, increase
code sharing across multiple mono processes and avoid just-in-time
compilation program startup costs.  The original assembly must still
be present, as the metadata is contained there.
.Sp
AOT code typically can not be moved from one computer to another
(CPU-specific optimizations that are detected at runtime) so you
should not try to move the pre-generated assemblies or package the
pre-generated assemblies for deployment.    
.Sp
A few options are available as a parameter to the 
.B --aot 
command line option.   The options are separated by commas, and more
than one can be specified:
.RS
.ne 8
.TP
.I bind-to-runtime-version
.Sp
If specified, forces the generated AOT files to be bound to the
runtime version of the compiling Mono.   This will prevent the AOT
files from being consumed by a different Mono runtime.
.I full
This is currently an experimental feature as it is not complete.
This instructs Mono to precompile code that has historically not been
precompiled with AOT.   
.TP
.I write-symbols
Instructs the AOT compiler to emit debug symbol information.
.ne
.RE
.Sp
For more information about AOT, see: http://www.mono-project.com/AOT
.TP
\fB--aot-only\fR
This is an experimental flag that instructs the Mono runtime to not
generate any code at runtime and depend exclusively on the code
generated from using mono --aot=full previously.   This is useful for
platforms that do not permit dynamic code generation.
.Sp
Notice that this feature will abort execution at runtime if a codepath
in your program, or Mono's class libraries attempts to generate code
dynamically.  You should test your software upfront and make sure that
you do not use any dynamic features.
.TP
\fB--config filename\fR
Load the specified configuration file instead of the default one(s).
The default files are /etc/mono/config and ~/.mono/config or the file
specified in the MONO_CONFIG environment variable, if set.  See the
mono-config(5) man page for details on the format of this file.
.TP
\fB--desktop\fR
Configures the virtual machine to be better suited for desktop
applications.  Currently this sets the GC system to avoid expanding
the heap as much as possible at the expense of slowing down garbage
collection a bit.
.TP
\fB--help\fR, \fB-h\fR
Displays usage instructions.
.TP
\fB--optimize=MODE\fR, \fB-O=MODE\fR
MODE is a comma separated list of optimizations.  They also allow
optimizations to be turned off by prefixing the optimization name with
a minus sign.
.Sp
In general, Mono has been tuned to use the default set of flags,
before using these flags for a deployment setting, you might want to
actually measure the benefits of using them.    
.Sp
The following optimizations are implemented:
.nf
             all        Turn on all optimizations
             peephole   Peephole postpass
             branch     Branch optimizations
             inline     Inline method calls
             cfold      Constant folding
             consprop   Constant propagation
             copyprop   Copy propagation
             deadce     Dead code elimination
             linears    Linear scan global reg allocation
             cmov       Conditional moves [arch-dependency]
             shared     Emit per-domain code
             sched      Instruction scheduling
             intrins    Intrinsic method implementations
             tailc      Tail recursion and tail calls
             loop       Loop related optimizations
             fcmov      Fast x86 FP compares [arch-dependency]
             leaf       Leaf procedures optimizations
             aot        Usage of Ahead Of Time compiled code
             precomp    Precompile all methods before executing Main
             abcrem     Array bound checks removal
             ssapre     SSA based Partial Redundancy Elimination
             sse2       SSE2 instructions on x86 [arch-dependency]
             gshared    Enable generic code sharing.
.fi
.Sp
For example, to enable all the optimization but dead code
elimination and inlining, you can use:
.nf
        -O=all,-deadce,-inline
.fi
.Sp
The flags that are flagged with [arch-dependency] indicate that the
given option if used in combination with Ahead of Time compilation
(--aot flag) would produce pre-compiled code that will depend on the
current CPU and might not be safely moved to another computer. 
.TP
\fB--runtime=VERSION\fR
Mono supports different runtime versions. The version used depends on the program
that is being run or on its configuration file (named program.exe.config). This option
can be used to override such autodetection, by forcing a different runtime version
to be used. Note that this should only be used to select a later compatible runtime
version than the one the program was compiled against. A typical usage is for
running a 1.1 program on a 2.0 version:
.nf
         mono --runtime=v2.0.50727 program.exe
.fi
.TP
\fB--security\fR, \fB--security=mode\fR
Activate the security manager, a currently experimental feature in
Mono and it is OFF by default. The new code verifier can be enabled
with this option as well.
.RS
.ne 8
.PP
Using security without parameters is equivalent as calling it with the
"cas" parameter.  
.PP
The following modes are supported:
.TP
.I cas
This allows mono to support declarative security attributes,
e.g. execution of Code Access Security (CAS) or non-CAS demands.
.TP 
.I core-clr
Enables the core-clr security system, typically used for
Moonlight/Silverlight applications.  It provides a much simpler
security system than CAS, see http://www.mono-project.com/Moonlight
for more details and links to the descriptions of this new system. 
.TP
.I validil
Enables the new verifier and performs basic verification for code
validity.  In this mode, unsafe code and P/Invoke are allowed. This
mode provides a better safety guarantee but it is still possible
for managed code to crash Mono. 
.TP
.I verifiable
Enables the new verifier and performs full verification of the code
being executed.  It only allows verifiable code to be executed.
Unsafe code is not allowed but P/Invoke is.  This mode should
not allow managed code to crash mono.  The verification is not as
strict as ECMA 335 standard in order to stay compatible with the MS
runtime.
.ne
.RE
.TP
\fB--server\fR
Configures the virtual machine to be better suited for server
operations (currently, a no-op).
.TP
\fB-V\fR, \fB--version\fR
Prints JIT version information (system configuration, release number
and branch names if available). 


.SH DEVELOPMENT OPTIONS
The following options are used to help when developing a JITed application.
.TP
\fB--debug\fR, \fB--debug=OPTIONS\fR
Turns on the debugging mode in the runtime.  If an assembly was
compiled with debugging information, it will produce line number
information for stack traces. 
.RS
.ne 8
.PP
The optional OPTIONS argument is a comma separated list of debugging
options.  These options are turned off by default since they generate
much larger and slower code at runtime.
.TP
The following options are supported:
.TP
.I casts
Produces a detailed error when throwing a InvalidCastException.
.TP
.I mdb-optimizations
Disable some JIT optimizations which are usually only disabled when
running inside the debugger.  This can be helpful if you want to attach
to the running process with mdb.
.ne
.RE
.TP
\fB--profile[=profiler[:profiler_args]]\fR
Turns on profiling.  For more information about profiling applications
and code coverage see the sections "PROFILING" and "CODE COVERAGE"
below. 
.TP
\fB--trace[=expression]\fR
Shows method names as they are invoked.  By default all methods are
traced. 
.Sp
The trace can be customized to include or exclude methods, classes or
assemblies.  A trace expression is a comma separated list of targets,
each target can be prefixed with a minus sign to turn off a particular
target.  The words `program', `all' and `disabled' have special
meaning.  `program' refers to the main program being executed, and
`all' means all the method calls.
.Sp
The `disabled' option is used to start up with tracing disabled.  It
can be enabled at a later point in time in the program by sending the
SIGUSR2 signal to the runtime.
.Sp
Assemblies are specified by their name, for example, to trace all
calls in the System assembly, use:
.nf

        mono --trace=System app.exe

.fi
Classes are specified with the T: prefix.  For example, to trace all
calls to the System.String class, use:
.nf

        mono --trace=T:System.String app.exe

.fi
And individual methods are referenced with the M: prefix, and the
standard method notation:
.nf

        mono --trace=M:System.Console:WriteLine app.exe

.fi
As previously noted, various rules can be specified at once:
.nf

        mono --trace=T:System.String,T:System.Random app.exe

.fi
You can exclude pieces, the next example traces calls to
System.String except for the System.String:Concat method.
.nf

        mono --trace=T:System.String,-M:System.String:Concat

.fi
Finally, namespaces can be specified using the N: prefix:
.nf

        mono --trace=N:System.Xml

.fi
.SH JIT MAINTAINER OPTIONS
The maintainer options are only used by those developing the runtime
itself, and not typically of interest to runtime users or developers.
.TP
\fB--break method\fR
Inserts a breakpoint before the method whose name is `method'
(namespace.class:methodname).  Use `Main' as method name to insert a
breakpoint on the application's main method.
.TP
\fB--breakonex\fR
Inserts a breakpoint on exceptions.  This allows you to debug your
application with a native debugger when an exception is thrown.
.TP
\fB--compile name\fR
This compiles a method (namespace.name:methodname), this is used for
testing the compiler performance or to examine the output of the code
generator. 
.TP
\fB--compileall\fR
Compiles all the methods in an assembly.  This is used to test the
compiler performance or to examine the output of the code generator
.TP 
\fB--graph=TYPE METHOD\fR
This generates a postscript file with a graph with the details about
the specified method (namespace.name:methodname).  This requires `dot'
and ghostview to be installed (it expects Ghostview to be called
"gv"). 
.Sp
The following graphs are available:
.nf
          cfg        Control Flow Graph (CFG)
          dtree      Dominator Tree
          code       CFG showing code
          ssa        CFG showing code after SSA translation
          optcode    CFG showing code after IR optimizations
.fi
.Sp
Some graphs will only be available if certain optimizations are turned
on.
.TP
\fB--ncompile\fR
Instruct the runtime on the number of times that the method specified
by --compile (or all the methods if --compileall is used) to be
compiled.  This is used for testing the code generator performance. 
.TP 
\fB--stats\fR
Displays information about the work done by the runtime during the
execution of an application. 
.TP
\fB--wapi=hps|semdel\fR
Perform maintenance of the process shared data.
.Sp
semdel will delete the global semaphore.
.Sp
hps will list the currently used handles.
.TP
\fB-v\fR, \fB--verbose\fR
Increases the verbosity level, each time it is listed, increases the
verbosity level to include more information (including, for example, 
a disassembly of the native code produced, code selector info etc.).
.SH PROFILING
The mono runtime includes a profiler that can be used to explore
various performance related problems in your application.  The
profiler is activated by passing the --profile command line argument
to the Mono runtime, the format is:
.nf

        --profile[=profiler[:profiler_args]]

.fi
Mono has a built-in profiler called 'default' (and is also the default
if no arguments are specified), but developers can write custom
profilers, see the section "CUSTOM PROFILERS" for more details.
.PP
If a 
.I profiler 
is not specified, the default profiler is used.
.Sp
The 
.I profiler_args 
is a profiler-specific string of options for the profiler itself.
.Sp
The default profiler accepts the following options 'alloc' to profile
memory consumption by the application; 'time' to profile the time
spent on each routine; 'jit' to collect time spent JIT-compiling methods
and 'stat' to perform sample statistical profiling.
If no options are provided the default is 'alloc,time,jit'. 
.PP
By default the
profile data is printed to stdout: to change this, use the 'file=filename'
option to output the data to filename.
.Sp
For example:
.nf

        mono --profile program.exe

.fi
.Sp
That will run the program with the default profiler and will do time
and allocation profiling.
.Sp
.nf

        mono --profile=default:stat,alloc,file=prof.out program.exe

.fi
Will do  sample statistical profiling and allocation profiling on
program.exe. The profile data is put in prof.out.
.Sp
Note that the statistical profiler has a very low overhead and should
be the preferred profiler to use (for better output use the full path
to the mono binary when running and make sure you have installed the
addr2line utility that comes from the binutils package).
.SH LOGGING PROFILER
.PP
The
.I logging profiler
will eventually replace the default profiler as it is more complete
and encompasses the functionality of all the other profiler for Mono.
It is able to track method execution times, allocations, jit times and
collect statistical data.  Instead of reporting the collected
information at the end of the execution of the program, it logs these
events periodically into a file during program execution.  The output
file contains compressed events, to process the data you should use
tools like the "Mono.Profiler" tool provided on the Mono SVN
repository.  
.nf

        mono --profile=logging[:OPTIONS] program.exe

.fi
.PP
To minimize the performance impact with multi-threaded applications,
the logging profiler keeps a per-thread buffer that is routinely saved
to disk.   
.PP
If specified, the options are separated by commas:
.RS
.ne 8
.TP
\fIoutput=FILE\fR, \fIout=FILE\fR or \fIo=FILE\fR
Use this option to provide the output file name for the profile log.
If this option is not specified, it will default to profiler-log.prof.
.TP
\fIjit\fR, \fIj\fR
Collect information about time spent by the JIT engine compiling
methods. 
.TP
\fIallocations\fR, \fIalloc\fR or \fIa\fR Collect 
information about each allocation (object class and size).
.TP
\fIenter-leave\fR, \fIcalls\fR or \fIc\fR
Measure the time spent inside each method call, this is done by
logging the time when a method enters and when the method leaves.
This can be a time consuming operation. 
.TP
\fIstatistical\fR, \fIstat\fR or \fIs\fR
Performs statistical profiling.   This is a lightweight profiling
mechanism as it has a much lower overhead than the \fIenter-leave\fR
profiling as it works by sampling where the program is spending its
time by using a timer. 
.TP
\fIunreachable\fR, \fIfree\fR or \fIf\fR
Performs a lighweight profile of the garbage collector.  On each
collection performed by the GC, the list of unreachable objects is
recorded, and for each object the class and size is provided.  This
information is useful to compute the heap size broken down by class.
.TP
\fIheap-shot\fR, \fIheap\fR or \fIh\fR
Performsn full heap profiling.   In this case on each
collection a full heap snapshot is recorded to disk.
.TP
\fIgc-commands=FILE\fR, \fIgc-c=FILE\fR or \fIgcc=FILE\fR 
Used to specify the file that controls the heap snapshot dumps.
.TP
\fIgc-dumps=N\fR, \fIgc-d=N\fR, \fIgcd=N\fR
Used to specify the initial number of heap snapshots to dump (if the control file is not used). 
.TP
\fIper-thread-buffer-size=N\fR, \fItbs=N\fR
Use to specify the number of events that a thread buffer
can hold.   When the thread buffer is full, the log block it is
written to disk.
.Sp
This defaults to tbs=10000.
.TP
\fIstatistical-thread-buffer-size=N\fR, \fIsbs=N\fR
The number of statistical samples that
are held in memory before they are dumped to disk (the system does
double-buffering and the statistical samples are written by a helper
thread).  
.Sp
This defaults to sbs=10000.
.TP
\fIwrite-buffer-size\fR, \fIwbs\fR
Specifies the size in bytes of the internal write buffers.
.Sp
This defaults to wbs=1024.
.ne
.RE
.PP
A few invocation samples follow.
.PP
To collect statistical data:
.nf

        mono --profile=logging:s program.exe
.fi
.PP
To profile method enter-exit and allocations:
.nf

        mono --profile=logging:c,a program.exe
.fi
.PP
To profile method enter-exit and jit time, and write the data to "mydata.mprof":
.nf

        mono --profile=logging:c,j,o=mydata.mprof program.exe
.fi
.PP
Then you would need to invoke the decoder on "mydata.mprof" to see the
profiling results.
.PP
In its current state, this profiler can also perform heap analysis (like
heap-shot), and the decoder is already able to read the data, however
the user interface for this feature has not yet been written (which means
that the data is not printed by the decoder).
.PP
More explanations are provided here: "http://www.mono-project.com/LoggingProfiler".
.SH EXTERNAL PROFILERS
There are a number of external profilers that have been developed for
Mono, we will update this section to contain the profilers.
.PP
The heap Shot profiler can track all live objects, and references to
these objects, and includes a GUI tool, this is our recommended
profiler.
To install you must download the profiler
from Mono's SVN:
.nf
        svn co svn://svn.myrealbox.com/source/trunk/heap-shot
        cd heap-shot
        ./autogen
        make
        make install
.fi
.PP
See the included documentation for details on using it.
.PP
The Live Type profiler shows at every GC iteration all of the live
objects of a given type.   To install you must download the profiler
from Mono's SVN:
.nf
        svn co svn://svn.myrealbox.com/source/trunk/heap-prof
        cd heap-prof
        ./autogen
        make
        make install
.fi
.PP
To use the profiler, execute:
.nf
        mono --profile=desc-heap program.exe
.fi
.PP
The output of this profiler looks like this:
.nf
        Checkpoint at 102 for heap-resize
           System.MonoType : 708
           System.Threading.Thread : 352
           System.String : 3230
           System.String[] : 104
           Gnome.ModuleInfo : 112
           System.Object[] : 160
           System.Collections.Hashtable : 96
           System.Int32[] : 212
           System.Collections.Hashtable+Slot[] : 296
           System.Globalization.CultureInfo : 108
           System.Globalization.NumberFormatInfo : 144
.fi
.PP
The first line describes the iteration number for the GC, in this case
checkpoint 102.
.PP
Then on each line the type is displayed as well as the number of bytes
that are being consumed by live instances of this object.
.PP 
The AOT profiler is used to feed back information to the AOT compiler
about how to order code based on the access patterns for pages.  To
use it, use:
.nf
        mono --profile=aot program.exe
.fi
The output of this profile can be fed back into Mono's AOT compiler to
order the functions on the disk to produce precompiled images that
have methods in sequential pages.
.SH CUSTOM PROFILERS
Mono provides a mechanism for loading other profiling modules which in
the form of shared libraries.  These profiling modules can hook up to
various parts of the Mono runtime to gather information about the code
being executed.
.PP
To use a third party profiler you must pass the name of the profiler
to Mono, like this:
.nf

        mono --profile=custom program.exe

.fi
.PP
In the above sample Mono will load the user defined profiler from the
shared library `mono-profiler-custom.so'.  This profiler module must
be on your dynamic linker library path.
.PP 
A list of other third party profilers is available from Mono's web
site (www.mono-project.com/Performance_Tips)
.PP
Custom profiles are written as shared libraries.  The shared library
must be called `mono-profiler-NAME.so' where `NAME' is the name of
your profiler.
.PP
For a sample of how to write your own custom profiler look in the
Mono source tree for in the samples/profiler.c.
.SH CODE COVERAGE
Mono ships with a code coverage module.  This module is activated by
using the Mono --profile=cov option.  The format is:
\fB--profile=cov[:assembly-name[/namespace]] test-suite.exe\fR
.PP
By default code coverage will default to all the assemblies loaded,
you can limit this by specifying the assembly name, for example to
perform code coverage in the routines of your program use, for example
the following command line limits the code coverage to routines in the
"demo" assembly:
.nf

        mono --profile=cov:demo demo.exe

.fi
.PP
Notice that the 
.I assembly-name
does not include the extension.
.PP
You can further restrict the code coverage output by specifying a
namespace:
.nf

        mono --profile=cov:demo/My.Utilities demo.exe

.fi
.PP
Which will only perform code coverage in the given assembly and
namespace.  
.PP
Typical output looks like this:
.nf

        Not covered: Class:.ctor ()
        Not covered: Class:A ()
        Not covered: Driver:.ctor ()
        Not covered: Driver:method ()
        Partial coverage: Driver:Main ()
                offset 0x000a

.fi
.PP
The offsets displayed are IL offsets.
.PP
A more powerful coverage tool is available in the module `monocov'.
See the monocov(1) man page for details.
.SH DEBUGGING
It is possible to obtain a stack trace of all the active threads in
Mono by sending the QUIT signal to Mono, you can do this from the
command line, like this:
.nf

        kill -QUIT pid

.fi
Where pid is the Process ID of the Mono process you want to examine.
The process will continue running afterwards, but its state is not
guaranteed.
.PP
.B Important:
this is a last-resort mechanism for debugging applications and should
not be used to monitor or probe a production application.  The
integrity of the runtime after sending this signal is not guaranteed
and the application might crash or terminate at any given point
afterwards.   
.PP
You can use the MONO_LOG_LEVEL and MONO_LOG_MASK environment variables
to get verbose debugging output about the execution of your
application within Mono.
.PP
The 
.I MONO_LOG_LEVEL
environment variable if set, the logging level is changed to the set
value. Possible values are "error", "critical", "warning", "message",
"info", "debug". The default value is "error". Messages with a logging
level greater then or equal to the log level will be printed to
stdout/stderr.
.PP
Use "info" to track the dynamic loading of assemblies.
.PP
.PP
Use the 
.I MONO_LOG_MASK
environment variable to limit the extent of the messages you get: 
If set, the log mask is changed to the set value. Possible values are
"asm" (assembly loader), "type", "dll" (native library loader), "gc"
(garbage collector), "cfg" (config file loader), "aot" (precompiler) and "all". 
The default value is "all". Changing the mask value allows you to display only 
messages for a certain component. You can use multiple masks by comma 
separating them. For example to see config file messages and assembly loader
messages set you mask to "asm,cfg".
.PP
The following is a common use to track down problems with P/Invoke:
.nf

        $ MONO_LOG_LEVEL="debug" MONO_LOG_MASK="dll" mono glue.exe

.fi
.PP
.SH SERIALIZATION
Mono's XML serialization engine by default will use a reflection-based
approach to serialize which might be slow for continuous processing
(web service applications).  The serialization engine will determine
when a class must use a hand-tuned serializer based on a few
parameters and if needed it will produce a customized C# serializer
for your types at runtime.  This customized serializer then gets
dynamically loaded into your application.
.PP
You can control this with the MONO_XMLSERIALIZER_THS environment
variable.
.PP
The possible values are 
.B `no' 
to disable the use of a C# customized
serializer, or an integer that is the minimum number of uses before
the runtime will produce a custom serializer (0 will produce a
custom serializer on the first access, 50 will produce a serializer on
the 50th use). Mono will fallback to an interpreted serializer if the
serializer generation somehow fails. This behavior can be disabled
by setting the option
.B `nofallback'
(for example: MONO_XMLSERIALIZER_THS=0,nofallback).
.SH ENVIRONMENT VARIABLES
.TP
\fBGC_DONT_GC\fR
Turns off the garbage collection in Mono.  This should be only used
for debugging purposes
.TP
\fBMONO_AOT_CACHE\fR
If set, this variable will instruct Mono to ahead-of-time compile new
assemblies on demand and store the result into a cache in
~/.mono/aot-cache. 
.TP
\fBMONO_CFG_DIR\fR
If set, this variable overrides the default system configuration directory
($PREFIX/etc). It's used to locate machine.config file.
.TP
\fBMONO_COM\fR
Sets the style of COM interop.  If the value of this variable is "MS"
Mono will use string marhsalling routines from the liboleaut32 for the
BSTR type library, any other values will use the mono-builtin BSTR
string marshalling.
.TP
\fBMONO_CONFIG\fR
If set, this variable overrides the default runtime configuration file
($PREFIX/etc/mono/config). The --config command line options overrides the
environment variable.
.TP
\fBMONO_DEBUG\fR
If set, enables some features of the runtime useful for debugging.
This variable should contain a comma separated list of debugging options.
Currently, the following options are supported:
.RS
.ne 8
.TP
\fBbreak-on-unverified\fR
If this variable is set, when the Mono VM runs into a verification
problem, instead of throwing an exception it will break into the
debugger.  This is useful when debugging verifier problems
.TP
\fBcollect-pagefault-stats\fR
Collects information about pagefaults.   This is used internally to
track the number of page faults produced to load metadata.  To display
this information you must use this option with "--stats" command line
option.
.TP
\fBdont-free-domains\fR
This is an Optimization for multi-AppDomain applications (most
commonly ASP.NET applications).  Due to internal limitations Mono,
Mono by default does not use typed allocations on multi-appDomain
applications as they could leak memory when a domain is unloaded. 
.Sp
Although this is a fine default, for applications that use more than
on AppDomain heavily (for example, ASP.NET applications) it is worth
trading off the small leaks for the increased performance
(additionally, since ASP.NET applications are not likely going to
unload the application domains on production systems, it is worth
using this feature). 
.TP
\fBhandle-sigint\fR
Captures the interrupt signal (Control-C) and displays a stack trace
when pressed.  Useful to find out where the program is executing at a
given point.  This only displays the stack trace of a single thread. 
.TP
\fBkeep-delegates\fR
This option will leak delegate trampolines that are no longer
referenced as to present the user with more information about a
delegate misuse.  Basically a delegate instance might be created,
passed to unmanaged code, and no references kept in managed code,
which will garbage collect the code.  With this option it is possible
to track down the source of the problems. 
.TP
\fBno-gdb-backtrace\fR
This option will disable the GDB backtrace emitted by the runtime
after a SIGSEGV or SIGABRT in unmanaged code.
.ne
.RE
.TP
\fBMONO_DISABLE_AIO\fR
If set, tells mono NOT to attempt using native asynchronous I/O services. In
that case, a default select/poll implementation is used. Currently only epoll()
is supported.
.TP
\fBMONO_DISABLE_MANAGED_COLLATION\fR
If this environment variable is `yes', the runtime uses unmanaged
collation (which actually means no culture-sensitive collation). It
internally disables managed collation functionality invoked via the
members of System.Globalization.CompareInfo class. Collation is
enabled by default.
.TP
\fBMONO_EGD_SOCKET\fR
For platforms that do not otherwise have a way of obtaining random bytes
this can be set to the name of a file system socket on which an egd or
prngd daemon is listening.
.TP
\fBMONO_EVENTLOG_TYPE\fR
Sets the type of event log provider to use (for System.Diagnostics.EventLog).
.Sp
Possible values are:
.RS
.TP
.I "local[:path]"
.Sp
Persists event logs and entries to the local file system.
.Sp
The directory in which to persist the event logs, event sources and entries
can be specified as part of the value.
.Sp
If the path is not explicitly set, it defaults to "/var/lib/mono/eventlog"
on unix and "%APPDATA%\mono\eventlog" on Windows.
.TP
.I "win32"
.Sp
.B 
Uses the native win32 API to write events and registers event logs and
event sources in the registry.   This is only available on Windows. 
.Sp
On Unix, the directory permission for individual event log and event source
directories is set to 777 (with +t bit) allowing everyone to read and write
event log entries while only allowing entries to be deleted by the user(s)
that created them.
.TP
.I "null"
.Sp
Silently discards any events.
.ne
.PP
The default is "null" on Unix (and versions of Windows before NT), and 
"win32" on Windows NT (and higher).
.RE
.TP
\fBMONO_EXTERNAL_ENCODINGS\fR
If set, contains a colon-separated list of text encodings to try when
turning externally-generated text (e.g. command-line arguments or
filenames) into Unicode.  The encoding names come from the list
provided by iconv, and the special case "default_locale" which refers
to the current locale's default encoding.
.IP
When reading externally-generated text strings UTF-8 is tried first,
and then this list is tried in order with the first successful
conversion ending the search.  When writing external text (e.g. new
filenames or arguments to new processes) the first item in this list
is used, or UTF-8 if the environment variable is not set.
.IP
The problem with using MONO_EXTERNAL_ENCODINGS to process your
files is that it results in a problem: although its possible to get
the right file name it is not necessarily possible to open the file.
In general if you have problems with encodings in your filenames you
should use the "convmv" program.
.TP
\fBMONO_GAC_PREFIX\fR
Provides a prefix the runtime uses to look for Global Assembly Caches.
Directories are separated by the platform path separator (colons on
unix). MONO_GAC_PREFIX should point to the top directory of a prefixed
install. Or to the directory provided in the gacutil /gacdir command. Example:
.B /home/username/.mono:/usr/local/mono/
.TP
\fBMONO_IOMAP\fR
Enables some filename rewriting support to assist badly-written
applications that hard-code Windows paths.  Set to a colon-separated
list of "drive" to strip drive letters, or "case" to do
case-insensitive file matching in every directory in a path.  "all"
enables all rewriting methods.  (Backslashes are always mapped to
slashes if this variable is set to a valid option.)
.fi
.Sp
For example, this would work from the shell:
.nf

        MONO_IOMAP=drive:case
        export MONO_IOMAP

.fi
If you are using mod_mono to host your web applications, you can use
the 
.B MonoSetEnv
directive, like this:
.nf

        MonoSetEnv MONO_IOMAP=all

.fi
.TP
\fBMONO_MANAGED_WATCHER\fR
If set to "disabled", System.IO.FileSystemWatcher will use a file watcher 
implementation which silently ignores all the watching requests.
If set to any other value, System.IO.FileSystemWatcher will use the default
managed implementation (slow). If unset, mono will try to use inotify, FAM, 
Gamin, kevent under Unix systems and native API calls on Windows, falling 
back to the managed implementation on error.
.TP
\fBMONO_NO_SMP\fR
If set causes the mono process to be bound to a single processor. This may be
useful when debugging or working around race conditions.
.TP
\fBMONO_PATH\fR
Provides a search path to the runtime where to look for library
files.   This is a tool convenient for debugging applications, but
should not be used by deployed applications as it breaks the assembly
loader in subtle ways. 
.Sp
Directories are separated by the platform path separator (colons on unix). Example:
.B /home/username/lib:/usr/local/mono/lib
.Sp
Alternative solutions to MONO_PATH include: installing libraries into
the Global Assembly Cache (see gacutil(1)) or having the dependent
libraries side-by-side with the main executable.
.Sp
For a complete description of recommended practices for application
deployment, see the
http://www.mono-project.com/Guidelines:Application_Deployment page. 
.TP
\fBMONO_RTC\fR
Experimental RTC support in the statistical profiler: if the user has
the permission, more accurate statistics are gathered.  The MONO_RTC
value must be restricted to what the Linux rtc allows: power of two
from 64 to 8192 Hz. To enable higher frequencies like 4096 Hz, run as root:
.nf

        echo 4096 > /proc/sys/dev/rtc/max-user-freq

.fi
.Sp
For example:
.nf

        MONO_RTC=4096 mono --profiler=default:stat program.exe

.fi
.TP
\fBMONO_NO_TLS\fR
Disable inlining of thread local accesses. Try setting this if you get a segfault
early on in the execution of mono.
.TP 
\fBMONO_SHARED_DIR\fR
If set its the directory where the ".wapi" handle state is stored.
This is the directory where the Windows I/O Emulation layer stores its
shared state data (files, events, mutexes, pipes).  By default Mono
will store the ".wapi" directory in the users's home directory.
.TP 
\fBMONO_SHARED_HOSTNAME\fR
Uses the string value of this variable as a replacement for the host name when
creating file names in the ".wapi" directory. This helps if the host name of
your machine is likely to be changed when a mono application is running or if
you have a .wapi directory shared among several different computers.
.Sp
Mono typically uses the hostname to create the files that are used to
share state across multiple Mono processes.  This is done to support
home directories that might be shared over the network.
.TP
\fBMONO_STRICT_IO_EMULATION\fR
If set, extra checks are made during IO operations.  Currently, this
includes only advisory locks around file writes.
.TP
\fBMONO_DISABLE_SHM\fR
If set, disables the shared memory files used for cross-process
handles: process have only private handles.  This means that process
and thread handles are not available to other processes, and named
mutexes, named events and named semaphores are not visible between
processes.
.Sp
This is can also be enabled by default by passing the
"--disable-shared-handles" option to configure.
.TP
\fBMONO_THEME\fR
The name of the theme to be used by Windows.Forms.   Available themes today
include "clearlooks", "nice" and "win32".
.Sp
The default is "win32".  
.TP
\fBMONO_TLS_SESSION_CACHE_TIMEOUT\fR
The time, in seconds, that the SSL/TLS session cache will keep it's entry to
avoid a new negotiation between the client and a server. Negotiation are very
CPU intensive so an application-specific custom value may prove useful for 
small embedded systems.
.Sp
The default is 180 seconds.
.TP
\fBMONO_THREADS_PER_CPU\fR
The maximum number of threads in the general threadpool will be
20 + (MONO_THREADS_PER_CPU * number of CPUs). The default value for this
variable is 5.
.TP
\fBMONO_XMLSERIALIZER_THS\fR
Controls the threshold for the XmlSerializer to produce a custom
serializer for a given class instead of using the Reflection-based
interpreter.  The possible values are `no' to disable the use of a
custom serializer or a number to indicate when the XmlSerializer
should start serializing.   The default value is 50, which means that
the a custom serializer will be produced on the 50th use.
.TP
\fBMONO_XMLSERIALIZER_DEBUG\fR
Set this value to 1 to prevent the serializer from removing the
temporary files that are created for fast serialization;  This might
be useful when debugging.
.TP
\fBMONO_ASPNET_INHIBIT_SETTINGSMAP\fR
Mono contains a feature which allows modifying settings in the .config files shipped
with Mono by using config section mappers. The mappers and the mapping rules are
defined in the $prefix/etc/mono/2.0/settings.map file and, optionally, in the
settings.map file found in the top-level directory of your ASP.NET application.
Both files are read by System.Web on application startup, if they are found at the
above locations. If you don't want the mapping to be performed you can set this
variable in your environment before starting the application and no action will
be taken.
.SH ENVIRONMENT VARIABLES FOR DEBUGGING
.TP
\fBMONO_ASPNET_NODELETE\fR
If set to any value, temporary source files generated by ASP.NET support
classes will not be removed. They will be kept in the user's temporary
directory.
.TP
\fBMONO_LOG_LEVEL\fR
The logging level, possible values are `error', `critical', `warning',
`message', `info' and `debug'.  See the DEBUGGING section for more
details.
.TP
\fBMONO_LOG_MASK\fR
Controls the domain of the Mono runtime that logging will apply to. 
If set, the log mask is changed to the set value. Possible values are
"asm" (assembly loader), "type", "dll" (native library loader), "gc"
(garbage collector), "cfg" (config file loader), "aot" (precompiler) and "all". 
The default value is "all". Changing the mask value allows you to display only 
messages for a certain component. You can use multiple masks by comma 
separating them. For example to see config file messages and assembly loader
messages set you mask to "asm,cfg".
.TP
\fBMONO_TRACE\fR
Used for runtime tracing of method calls. The format of the comma separated
trace options is:
.nf

        [-]M:method name
        [-]N:namespace
        [-]T:class name
        [-]all
        [-]program
        disabled                Trace output off upon start.

.fi
You can toggle trace output on/off sending a SIGUSR2 signal to the program.
.TP
\fBMONO_TRACE_LISTENER\fR
If set, enables the System.Diagnostics.DefaultTraceListener, which will 
print the output of the System.Diagnostics Trace and Debug classes.  
It can be set to a filename, and to Console.Out or Console.Error to display
output to standard output or standard error, respectively. If it's set to
Console.Out or Console.Error you can append an optional prefix that will
be used when writing messages like this: Console.Error:MyProgramName.
See the System.Diagnostics.DefaultTraceListener documentation for more
information.
.TP
\fBMONO_XEXCEPTIONS\fR
This throws an exception when a X11 error is encountered; by default a
message is displayed but execution continues
.TP
\fBMONO_XSYNC\fR
This is used in the System.Windows.Forms implementation when running
with the X11 backend.  This is used to debug problems in Windows.Forms
as it forces all of the commands send to X11 server to be done
synchronously.   The default mode of operation is asynchronous which
makes it hard to isolate the root of certain problems.
.TP
\fBMONO_GENERIC_SHARING\fR
This environment variable controls the kind of generic sharing used.
This variable is used by internal JIT developers and should not be
changed in production.  Do not use it.
.Sp
The variable controls which classes will have generic code sharing
enabled.
.Sp
Permissible values are:
.RS
.TP 
.I "all" 
All generated code can be shared. 
.TP
.I "collections" 
Only the classes in System.Collections.Generic will have its code
shared (this is the default value).
.TP
.I "corlib"
Only code in corlib will have its code shared.
.TP
.I "none"
No generic code sharing will be performed.
.RE
.Sp
Generic code sharing by default only applies to collections.   The
Mono JIT by default turns this on.
.SH VALGRIND
If you want to use Valgrind, you will find the file `mono.supp'
useful, it contains the suppressions for the GC which trigger
incorrect warnings.  Use it like this:
.nf
    valgrind --suppressions=mono.supp mono ...
.fi
.SH DTRACE
On some platforms, Mono can expose a set of DTrace probes (also known
as user-land statically defined, USDT Probes).
.TP
They are defined in the file `mono.d'.
.TP
.B ves-init-begin, ves-init-end
.Sp
Begin and end of runtime initialization.
.TP
.B method-compile-begin, method-compile-end
.Sp
Begin and end of method compilation.
The probe arguments are class name, method name and signature,
and in case of method-compile-end success or failure of compilation.
.TP
.B gc-begin, gc-end
.Sp
Begin and end of Garbage Collection.
.TP
To verify the availability of the probes, run:
.nf
    dtrace -P mono'$target' -l -c mono
.fi
.SH FILES
On Unix assemblies are loaded from the installation lib directory.  If you set
`prefix' to /usr, the assemblies will be located in /usr/lib.  On
Windows, the assemblies are loaded from the directory where mono and
mint live.
.TP
.B ~/.mono/aot-cache
.Sp
The directory for the ahead-of-time compiler demand creation
assemblies are located. 
.TP
.B /etc/mono/config, ~/.mono/config
.Sp
Mono runtime configuration file.  See the mono-config(5) manual page
for more information.
.TP
.B ~/.config/.mono/certs, /usr/share/.mono/certs
.Sp
Contains Mono certificate stores for users / machine. See the certmgr(1) 
manual page for more information on managing certificate stores and
the mozroots(1) page for information on how to import the Mozilla root
certificates into the Mono certificate store. 
.TP
.B ~/.mono/assemblies/ASSEMBLY/ASSEMBLY.config
.Sp
Files in this directory allow a user to customize the configuration
for a given system assembly, the format is the one described in the
mono-config(5) page. 
.TP
.B ~/.config/.mono/keypairs, /usr/share/.mono/keypairs
.Sp
Contains Mono cryptographic keypairs for users / machine. They can be 
accessed by using a CspParameters object with DSACryptoServiceProvider
and RSACryptoServiceProvider classes.
.TP
.B ~/.config/.isolatedstorage, ~/.local/share/.isolatedstorage, /usr/share/.isolatedstorage
.Sp
Contains Mono isolated storage for non-roaming users, roaming users and 
local machine. Isolated storage can be accessed using the classes from 
the System.IO.IsolatedStorage namespace.
.TP
.B <assembly>.config
.Sp
Configuration information for individual assemblies is loaded by the
runtime from side-by-side files with the .config files, see the
http://www.mono-project.com/Config for more information.
.TP
.B Web.config, web.config
.Sp
ASP.NET applications are configured through these files, the
configuration is done on a per-directory basis.  For more information
on this subject see the http://www.mono-project.com/Config_system.web
page. 
.SH MAILING LISTS
Mailing lists are listed at the
http://www.mono-project.com/Mailing_Lists
.SH WEB SITE
http://www.mono-project.com
.SH SEE ALSO
.PP
certmgr(1), mcs(1), monocov(1), monodis(1), mono-config(5), mozroots(1), xsp(1).
.PP
For more information on AOT:
http://www.mono-project.com/AOT
.PP
For ASP.NET-related documentation, see the xsp(1) manual page