mono - Mono's ECMA-CLI native code generator (Just-in-Time and Ahead-of-Time)

mono [options] file [arguments...]

mono is a runtime implementation of the ECMA Common Language Infrastructure. This can be used to run ECMA and .NET applications.

The runtime contains a native code generator that transforms the Common Intermediate Language into native code.

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.

The runtime loads ths specified file and optionally passes the arguments to it. The file is an ECMA assembly. They typically have a .exe or .dll extension.

The runtime provides a number of configuration options for running applications, for developping and debugging, and for testing and debugging the runtime itself.

The following options are available:

--aot

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. 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. 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. 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 availble on the generated file. When precompiling code, you might want to compile with all optimizations (-O=all). Pre-compiled code is position independent code. Pre compilation is just a mechanism to reduce startup time, and avoid just-in-time compilation costs. The original assembly must still be present, as the metadata is contained there.

--config filename

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.

--desktop

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.

--help , -h

Displays usage instructions.

--optimize=MODE , -O=mode

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. The following optimizations are implemented:

             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
             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
             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

For example, to enable all the optimization but dead code elimination and inlining, you can use:

	-O=all,-deadce,-inline

--security

Activate the security manager (experimental feature in 1.1). This allows mono to support declarative security attributes (e.g. execution of, CAS or non-CAS, security demands). The security manager is OFF by default (experimental).

--server

Configures the virtual machine to be better suited for server operations.

-V , --version

Prints JIT version information.

The following options are used to help when developing a JITed application.

--debug

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.

--profile[=profiler[:profiler_args]]

Turns on profiling. For more information about profiling applications and code coverage see the sections "PROFILING" and "CODE COVERAGE" below.

--trace[=expression]

Shows method names as they are invoked. By default all methods are traced. 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' and `all' have special meaning. `program' refers to the main program being executed, and `all' means all the method calls. Assemblies are specified by their name, for example, to trace all calls in the System assembly, use:

mono --trace=System app.exe

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

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

And individual methods are referenced with the M: prefix, and the standar method notation:

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

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

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

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

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

Finally, namespaces can be specified using the N: prefix:

mono --trace=N:System.Xml

The maintainer options are only used by those developing the runtime itself, and not typically of interest to runtime users or developers.

--break method

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.

--breakonex

Inserts a breakpoint on exceptions. This allows you to debug your application with a native debugger when an exception is thrown.

--compile name

This compiles a method (namespace.name:methodname), this is used for testing the compiler performance or to examine the output of the code generator.

--compileall

Compiles all the methods in an assembly. This is used to test the compiler performance or to examine the output of the code generator

--graph=TYPE METHOD

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"). The following graphs are available:

          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

Some graphs will only be available if certain optimizations are turned on.

--ncompile

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.

--stats

Displays information about the work done by the runtime during the execution of an application.

-v , --verbose

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.).

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:

--profile[=profiler[:profiler_args]]

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.

If a profiler is not specified, the default profiler is used. The profiler_args is a profiler-specific string of options for the profiler itself. The default profiler accepts the following options 'alloc' to profile memory consumption by the application; 'time' to profile the time spent on each routine and 'stat' to perform sample statistical profiling. If no options are provided the default is 'alloc,time'. For example:

mono --profile program.exe

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

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

Will do sample statistical profiling and allocation profiling on program.exe.

There are a number of external profilers that have been developed for Mono, we will update this section to contain the profilers.

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:

	svn co svn://svn.myrealbox.com/source/trunk/heap-prof
	cd heap-prof
	./autogen
	make
	make install

To use the profiler, execute:

	mono --profile=desc-heap program.exe

The output of this profiler looks like this:

	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

The first line describes the iteration number for the GC, in this case checkpoint 102.

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.

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.

To use a third party profiler you must pass the name of the profiler to Mono, like this:

mono --profile=custom program.exe

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.

A list of other third party profilers is available from Mono's web site (www.mono-project.com/Performance_Tips)

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.

For a sample of how to write your own custom profiler look in the Mono source tree for in the samples/profiler.c.

Mono ships with a code coverage module. This module is activated by using the Mono --profile=cov option. The format is: --profile=cov[:assembly-name[/namespace]] test-suite.exe

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:

mono --profile=cov:demo demo.exe

Notice that the assembly-name does not include the extension.

You can further restrict the code coverage output by specifying a namespace:

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

Which will only perform code coverage in the given assembly and namespace.

Typical output looks like this:

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

The offsets displayed are IL offsets.

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:

	kill -QUIT pid

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.

The 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.

Use "info" to track the dynamic loading of assemblies.

Use the 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".

The following is a common use to track down problems with P/Invoke:

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

Mono's XML serialization engine by default will use a reflection-based approach to serialize which might be slow for continous 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.

You can control this with the MONO_XMLSERIALIZER_THS environment variable.

The possible values are `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).

GC_DONT_GC

Turns off the garbage collection in Mono. This should be only used for debugging purposes

MONO_AOT_CACHE

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.

MONO_ASPNET_NODELETE

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.

MONO_CFG_DIR

If set, this variable overrides the default system configuration directory ($PREFIX/etc). It's used to locate machine.config file.

MONO_CONFIG

If set, this variable overrides the default runtime configuration file ($PREFIX/etc/mono/config). The --config command line options overrides the environment variable.

MONO_DEBUG

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:

collect-pagefault-stats

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.

handle-sigint

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.

keep-delegates

This option will leak delegate trampolines that are no longer referenced as to present the user with more information about a delegate missuse. 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.

MONO_DISABLE_AIO

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.

MONO_EGD_SOCKET

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.

MONO_EXTERNAL_ENCODINGS

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.

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.

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.

MONO_GAC_PREFIX

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: /home/username/.mono:/usr/local/mono/

MONO_LOG_LEVEL

The logging level, possible values are `error', `critical', `warning', `message', `info' and `debug'. See the DEBUGGING section for more details.

MONO_LOG_MASK

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".

MONO_MANAGED_WATCHER

If set to any value, System.IO.FileSystemWatcher will use the default managed implementation (slow). If unset, mono will try to use FAM under Unix systems and native API calls on Windows, falling back to the managed implementation on error.

MONO_PATH

Provides a search path to the runtime where to look for library files. Directories are separated by the platform path separator (colons on unix). Example: /home/username/lib:/usr/local/mono/lib

MONO_RTC

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:

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

For example:

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

MONO_NO_TLS

Disable inlining of thread local accesses. Try setting this if you get a segfault early on in the execution of mono.

MONO_SHARED_DIR

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.

MONO_SHARED_HOSTNAME

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. 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.

MONO_THEME

The name of the theme to be used by Windows.Forms. Available themes today include "clearlooks", "nice" and "win32". The default is "win32".

MONO_THREADS_PER_CPU

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.

MONO_TRACE

Used for runtime tracing of method calls. The format of the comma separated trace options is:

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

You can toggle trace output on/off sending a SIGUSR2 signal to the program.

MONO_TRACE_LISTENER

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.

MONO_DISABLE_MANAGED_COLLATION

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.

MONO_XMLSERIALIZER_THS

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.

MONO_STRICT_IO_EMULATION

If set, extra checks are made during IO operations. Currently, this includes only advisory locks around file writes.

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.

~/.mono/aot-cache

The directory for the ahead-of-time compiler demand creation assemblies are located.

/etc/mono/config, ~/.mono/config

Mono runtime configuration file. See the mono-config(5) manual page for more information.

~/.config/.mono/certs, /usr/share/.mono/certs

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.

~/.config/.mono/keypairs, /usr/share/.mono/keypairs

Contains Mono cryptographic keypairs for users / machine. They can be accessed by using a CspParameters object with DSACryptoServiceProvider and RSACryptoServiceProvider classes.

~/.config/.isolatedstorage, ~/.local/share/.isolatedstorage, /usr/share/.isolatedstorage

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.

Mailing lists are listed at the http://www.mono-project.com/Mailing_Lists

http://www.mono-project.com

certmgr(1),mcs(1),mint(1),monodis(1),mono-config(5),mozroots(1).

For ASP.NET-related documentation, see the xsp(1) manual page