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mcs(1)			    General Commands Manual			mcs(1)

       mcs - Mono C# Compiler

       mcs [option] [source-files]

       mcs is the Mono C# compiler, an implementation of the ECMA-334 language
       specification.  You can pass one	or more	options	to drive the compiler,
       and  a set of source files.  Extra options or arguments can be provided
       in a response file.  Response files are referenced by prepending	the  @
       symbol to the response file name.

       The  mcs	compiler is used to compile against the	latest Mono Base Class
       Library version and fully implements C# 1.0, 2.0, 3.0 and 4.0  specifi-

       See the section on packages for more information.

       The Mono	C# compiler accepts the	same command line options that the Mi-
       crosoft C# compiler does.  Those	options	can start with a  slash	 or  a
       dash  (/checked	is  the	same as	-checked).  Additionally some GNU-like
       options are supported, those begin with "--".  All  MCS-specific	 flags
       which are not available in the Microsoft	C# compiler are	available only
       with the	GNU-style options.

       C# source files must end	with a ".cs"  extension.   Compilation	of  C#
       source  code  requires  all the files that make up a library, module or
       executable to be	provided on the	command	line.  There is	no support for
       partial	compilation.   To achieve the benefits of partial compilation,
       you should compile programs into	their own assemblies, and later	refer-
       ence them with the "-r" flag.

       The  Mono  C#  compiler	generates images (.exe files) that contain CIL
       byte code that can be executed by any system that implements  a	Common
       Language	Infrastructure virtual machine such as the Microsoft .NET run-
       time engine on Windows or the Mono runtime engine on Unix systems.  Ex-
       ecutables are not bound to a specific CPU or operating system.

       The  Mono  C#  compiler	by  default  only references three assemblies:
       mscorlib.dll, System.dll	and System.Xml.dll.   If you want to reference
       extra  libraries	you must manually specify them using the -pkg: command
       line option or the -r: command line option.  Alternatively if you  want
       to get all of the System	libraries, you can use the -pkg:dotnet command
       line option.

	      Displays information about the Mono C# compiler

	      Includes the specified modules in	the resulting assembly.	  Mod-
	      ules are created by calling the compiler with the	-target:module

       -checked, -checked+
	      Sets the default compilation mode	to `checked'.  This makes  all
	      the math operations checked (the default is unchecked).

	      Sets  the	 default  compilation mode to `unchecked'.  This makes
	      all the math operations unchecked	(this is the default).

       -clscheck-, -clscheck+
	      Disables or enables  the	Common	Language  Specification	 (CLS)
	      checks (it is enabled by default).

	      The Common Language Specification	(CLS) defines an interoperable
	      subset of	types as well as conventions that compilers (CLS  pro-
	      ducers)  and developers must follow to expose code to other pro-
	      gramming languages (CLS consumers).

	      Specifies	the code page used to process the input	files from the
	      point it is specified on.	 By default files will be processed in
	      the environment-dependent	native code page.  The	compiler  will
	      also  automatically  detect  Unicode files that have an embedded
	      byte mark	at the beginning.

	      Other popular encodings are 28591	 (Latin1),  1252  (iso-8859-1)
	      and 65001	(UTF-8).

	      MCS supports a couple of shorthands: "utf8" can be used to spec-
	      ify utf-8	instead	of using the cryptic  65001  and  "reset"  re-
	      stores  the  automatic handling of code pages.  These shorthands
	      are not available	on the Microsoft compiler.

       -define:SYMLIST,	-d:SYMLIST
	      Defines the symbol listed	by the semi-colon separated list  SYM-
	      LIST  SYMBOL.  This can be tested	in the source code by the pre-
	      processor, or can	be used	by methods that	have been tagged  with
	      the Conditional attribute.

       -debug, -debug+
	      Generate	debugging information. To obtain stack traces with de-
	      bugging information, you need to invoke the  mono	 runtime  with
	      the `--debug' flag. The debugging	information is stored in a MDB
	      file located in same output folder as produced assembly.

	      Do not generate debugging	information.

	      Only embed the strongname	public key into	the assembly. The  ac-
	      tual  signing  must  be done in a	later stage using the SN tool.
	      This is useful to	protect	the private  key  during  development.
	      Note  that delay signing can only	be done	using a	strongname key
	      file (not	a key container). The option is	equivalent to  includ-
	      ing  [assembly:  AssemblyDelaySign  (true)] in your source code.
	      Compiler option takes precedence over the	attributes.

	      Default. Strongname (sign) the assembly using  the  strong  name
	      key  file	 (or container). The option is equivalent to including
	      [assembly: AssemblyDelaySign (false)] in your source code.  Com-
	      piler option takes precedence over the attributes.

	      Extracts	the  C#/XML  documentation  from  the  source code and
	      stores in	in the given FILE.

	      This flag	is ignored by Mono's C#	compiler and is	 present  only
	      to allow MCS to be used as a CSC replacement for msbuild/xbuild.

	      This  is	used for debugging the compiler.  This makes the error
	      emission generate	an exception that can be caught	by a debugger.

	      This flag	is ignored by Mono's C#	compiler and is	 present  only
	      to allow MCS to be used as a CSC replacement for msbuild/xbuild.

	      Any source code error or warning issued by the compiler includes
	      file name	only by	default. This option causes compiler to	 issue
	      absolute file path instead.

	      Strongname (sign)	the output assembly using the key pair present
	      in the specified strong name key file (snk). A full key pair  is
	      required	by default (or when using delaysign-). A file contain-
	      ing only the public key can be used with delaysign+. The	option
	      is  equivalent  to  including  [assembly:	AssemblyKeyFile	("KEY-
	      FILE")] in your source code.  Compiler option  takes  precedence
	      over the attributes.

	      Strongname (sign)	the output assembly using the key pair present
	      in the specified container. Note that delaysign+ is ignored when
	      using key	containers. The	option is equivalent to	including [as-
	      sembly: AssemblyKeyName ("CONTAINER")] in	your source code. Com-
	      piler option takes precedence over the attributes.

	      The  option  specifies  the  version of the language to use. The
	      feature set is different in each C# version. This	switch can  be
	      used  to	force  the compiler to allow only a subset of the fea-
	      tures.  The possible values are:

		     Instruct compiler to use the latest  version.  Equivalent
		     is	 to omit the switch (this currently defaults to	the C#
		     4.0 language specification).

	      ISO-1  Restrict compiler to use only first ISO standardized fea-
		     tures.   The  usage  of features such as generics,	static
		     classes, anonymous	methods	will lead to error.

	      ISO-2  Restrict compiler to use only the second ISO standardized
		     features.	 This  allows  the  use	 of  generics,	static
		     classes, iterators	and anonymous methods for example.

	      3	     Restrict the compiler to use only the features  available
		     in	C# 3.0 (a superset of ISO-1 and	ISO-2).

	      4	     Restrict  the compiler to use only	the features available
		     in	C# 4.0 specification.

		     Enables unstable features from upcoming versions  of  the

	      Notice  that  this  flag	only  restricts	 the language features
	      available	to the programmer. A version  of  produced  assemblies
	      can be controlled	using SDK option.

	      Each  path specified in the comma-separated list will direct the
	      compiler to look for libraries in	that specified path.

       -L PATH
	      Directs the compiler to look  for	 libraries  in	the  specified
	      path.  Multiple paths can	be provided by using the option	multi-
	      ple times.

	      Tells the	compiler which CLASS contains the entry	point.	Useful
	      when you are compiling several classes with a Main method.

       -nostdlib, -nostdlib+
	      Use  this	 flag  if  you want to compile the core	library.  This
	      makes the	compiler load its internal types from the assembly be-
	      ing compiled.

       -noconfig, -noconfig+
	      Disables	the  default compiler configuration to be loaded.  The
	      compiler by default has references to the	system assemblies.

	      Makes the	compiler ignore	warnings specified in the  comma-sepa-
	      rated list WARNLIST>

       -optimize, -optimize+, -optimize-
	      Controls compiler	code generation	optimizations on the code. Us-
	      ing -optimize or -optimize+ will turn on	optimizations,	-opti-
	      mize- will turn it off.  The default in mcs is to	optimize-. The
	      option can be mixed with -debug but for the best debugging expe-
	      rience it	is recommended leave the options off.

       -out:FNAME, -o FNAME
	      Names the	output file to be generated.

	      Used  for	 benchmarking.	The compiler will only parse its input

	      Reference	assemblies for the given packages.

	      The compiler will	invoke pkg-config --libs on the	set  of	 pack-
	      ages  specified  on the command line to obtain libraries and di-
	      rectories	to compile the code.

	      This is typically	used with third	party components, like this:

			$ mcs -pkg:gtk-sharp demo.cs

		     This will instruct	the compiler to	reference the System.*
		     libraries available on a typical dotnet framework instal-
		     lation, notice that this does not include all of the Mono
		     libraries,	 only the System.* ones.  This is a convenient
		     shortcut for those	porting	code.

	      Used to specify the target platform. The	possible  values  are:
	      anycpu,  anycpu32bitpreferred, arm, x86, x64 or itanium. The de-
	      fault option is anycpu.

	      Embeds to	the given resource file.  The optional ID can be  used
	      to give a	different name to the resource.	 If not	specified, the
	      resource name will be the	file name.

	      Links to the specified RESOURCE.	The optional ID	can be used to
	      give a name to the linked	resource.

       -r:ASSEMBLY1[,ASSEMBLY2], -reference ASSEMBLY1[,ASSEMBLY2]
	      Reference	 the  named  assemblies.  Use this to use classes from
	      the named	assembly in your program.  The assembly	will be	loaded
	      from  either the system directory	where all the assemblies live,
	      or from the path explicitly given	with the -L option.

	      You can also use a semicolon to separate the assemblies  instead
	      of a comma.

	      Extern alias reference support for C#.

	      If  you  have  different assemblies that provide the same	types,
	      the extern alias support allows you to provide names  that  your
	      software	can use	to tell	those appart.	 The types from	ASSEM-
	      BLY will be exposed as ALIAS, then on the	C#  source  code,  you
	      need to do:

		   extern alias	ALIAS;
	      To bring it into your namespace.	 For example, to cope with two
	      graphics	libraries  that	 define	  "Graphics.Point",   one   in
	      "OpenGL.dll"  and	 one in	"Postscript.dll", you would invoke the
	      compiler like this:

		   mcs -r:Postscript=Postscript.dll -r:OpenGL=OpenGL.dll

	      And in your source code, you would write:

		   extern alias	Postscript;
		   extern alias	OpenGL;

		   class X {
			// This	is a Graphics.Point from Postscrip.dll
			Postscript.Point p = new Postscript.Point ();

			// This	is a Graphics.Point from OpenGL.dll
			OpenGL.Point p = new OpenGL.Point ();

       -recurse:PATTERN, --recurse PATTERN
	      Does recursive compilation using the specified pattern.  In Unix
	      the  shell  will	perform	 globbing, so you might	want to	use it
	      like this:

		 $ mcs -recurse:'*.cs'

	      Used to specify the version of  Base  Class  Library  assemblies
	      used  for	compilation. Following predefined values are valid: 2,
	      4	(default) as well as any custom	value. The predefined  version
	      number  means  which  custom  value is specified mcs will	try to
	      find Base	Class Libraries	in the mono  installed	location  PRE-

	      Starts up	the compiler in	interactive mode, providing a C# shell
	      for statements and expressions.	 A  shortcut  is  to  use  the
	      csharp command directly.

	      Generates	 a stack trace at the time the error is	reported, use-
	      ful for debugging	the compiler.

       -target:KIND, -t:KIND
	      Used to specify the desired target.  The	possible  values  are:
	      exe  (plain  executable),	winexe (Windows.Forms executable), li-
	      brary (component libraries) and module (partial library).

	      Another debugging	flag.  Used to display the  times  at  various
	      points in	the compilation	process.

       -unsafe,	-unsafe+
	      Enables compilation of unsafe code.

       -v     Debugging. Turns on verbose yacc parsing.

	      Shows the	compiler version.

       -warnaserror, -warnaserror+
	      All compilers warnings will be reported as errors.

       -warnaserror:W1,[Wn], -warnaserror+:W1,[Wn]
	      Treats one or more compiler warnings as errors.

	      Sets  one	 or  more  compiler  warnings to be always threated as
	      warnings.	 Becomes useful	when used together with	-warnaserror.

	      Sets the warning level.  0 is the	lowest warning level, and 4 is
	      the highest.  The	default	is 4.

	      Specifies	 a  Win32  resource file (.res)	to be bundled into the
	      resulting	assembly.

	      Attaches the icon	specified in FILE on the output	into  the  re-
	      sulting assembly.

       --     Use this to stop option parsing, and allow option-looking	param-
	      eters to be passed on the	command	line.

       When referencing	an assembly, if	the name of the	assembly  is  a	 path,
       the  compiler will try to load the assembly specified in	the path.   If
       it does not, then the compiler will try loading the assembly  from  the
       current	directory,  the	compiler base directory	and if the assembly is
       not found in any	of those places	in the directories specified as	 argu-
       ments to	the -lib: command argument.

       The  compiler uses the library path to locate libraries,	and is able to
       reference libraries from	a particular  package  if  that	 directory  is
       used.   To  simplify  the use of	packages, the C# compiler includes the
       -pkg: command line option that is used to load specific collections  of

       Libraries  visible to the compiler are stored relative to the installa-
       tion prefix under PREFIX/lib/mono/ called the PACKAGEBASE and  the  de-
       faults for mcs, gmcs and	smcs are as follows:

       mcs    References the PACKAGEBASE/1.0 directory

       gmcs   References the PACKAGEBASE/2.0 directory

       smcs   References the PACKAGEBASE/2.1 directory

       Those  are the only runtime profiles that exist.	 Although other	direc-
       tories exist (like 3.0 and 3.5) those are not really runtime  profiles,
       they  are merely	placeholders for extra libraries that build on the 2.0

       Software	providers will distribute software that	is installed  relative
       to the PACKAGEBASE directory.  This is integrated into the gacutil tool
       that not	only installs public assemblies	into the Global	Assembly Cache
       (GAC)  but also installs	them into the PACKAGEBASE/PKG directory	(where
       PKG is the name passed to the -package flag to gacutil).

       As a developer, if you want to consume the Gtk#	libraries,  you	 would
       invoke the compiler like	this:

	    $ mcs -pkg:gtk-sharp-2.0 main.cs

       The  -pkg:  option  instructs the compiler to fetch the definitions for
       gtk-sharp-2.0 from pkg-config, this is equivalent to passing to the  C#
       compiler	the output of:

	    $ pkg-config --libs	gtk-sharp-2.0

       Usually this merely references the libraries from PACKAGEBASE/PKG.

       Although	 there are directory names for 3.0 and 3.5, that does not mean
       that there are 3.0 and 3.5 compiler editions or profiles.    Those  are
       merely  new  libraries that must	be manually referenced either with the
       proper -pkg: invocation,	or by referencing the libraries	directly.

       The TRACE and DEBUG defines have	a special meaning to the compiler.

       By default calls	to  methods  and  properties  in  the  System.Diagnos-
       tics.Trace  class  are not generated unless the TRACE symbol is defined
       (either through a "#define TRACE") in your source code, or by using the
       --define	TRACE in the command line.

       By  default  calls  to  methods	and  properties	in the System.Diagnos-
       tics.Debug class	are not	generated unless the DEBUG symbol  is  defined
       (either through a "#define DEBUG") in your source code, or by using the
       --define	DEBUG in the command line.

       Note that the effect of defining	TRACE and DEBUG	is a  global  setting,
       even if they are	only defined in	a single file.

       When  using the "-debug"	flag, MCS will generate	a file with the	exten-
       sion .mdb that contains the debugging information for the generated as-
       sembly.	This file is consumed by the Mono debugger (mdb).

	      If this variable is set, it contains a string in the form	"fore-
	      ground,background" that specifies	which color to use to  display
	      errors on	some terminals.

	      The background is	optional and defaults to your terminal current
	      background.   The	possible colors	 for  foreground  are:	black,
	      red,  brightred, green, brightgreen, yellow, brightyellow, blue,
	      brightblue,  magenta,  brightmagenta,  cyan,  brightcyan,	 grey,
	      white and	brightwhite.

	      The  possible colors for background are: black, red, green, yel-
	      low, blue, magenta, cyan,	grey and white.

	      For example, you could set these variable	from your shell:
		   export MCS_COLORS

	      You can disable the built-in color scheme	by setting this	 vari-
	      able to "disable".

       During compilation the MCS compiler defines the __MonoCS__ symbol, this
       can be used by pre-processor instructions to compile Mono  C#  compiler
       specific	 code.	  Please note that this	symbol is only to test for the
       compiler, and is	not useful to distinguish  compilation	or  deployment

       The  Mono C# Compiler was written by Miguel de Icaza, Ravi Pratap, Mar-
       tin Baulig, Marek Safar and Raja	Harinath.  The development was	funded
       by Ximian, Novell and Marek Safar.

       The  Mono  Compiler Suite is released under the terms of	the GNU	GPL or
       the MIT X11.  Please read the accompanying `COPYING' file for  details.
       Alternative licensing for the compiler is available from	Xamarin.

       csharp(1), mdb(1), mono(1), mopen(1), pkg-config(1), sn(1)

       To  report bugs in the compiler,	you must file them on our bug tracking
       system, at:

       The Mono	Mailing	lists are listed at

       The  Mono  C#  compiler	was  developed by Novell, Inc (http://www.nov-	and Xamarin Inc	( is based on the  ECMA
       C#	   language	     standard	       available	 here:

       The  home  page	for  the  Mono	C#  compiler  is  at  http://www.mono-

				6 January 2001				mcs(1)


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