Skip to content
Find file
Fetching contributors…
Cannot retrieve contributors at this time
528 lines (520 sloc) 18.8 KB
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
.TH mcs 1 "6 January 2001"
mcs \- Mono C# Compiler
.B 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.
.I 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 specifications.
See the section on packages for more information.
The Mono C# compiler accepts the same command line options that the
Microsoft 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 reference 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
runtime engine on Windows or the Mono runtime engine on Unix systems.
Executables 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.
.I \-\-about
Displays information about the Mono C# compiler
.I \-\-addmodule:MODULE1[,MODULE2]
Includes the specified modules in the resulting assembly. Modules are
created by calling the compiler with the -target:module option
.I -checked, -checked+
Sets the default compilation mode to `checked'. This makes all
the math operations checked (the default is unchecked).
.I -checked-
Sets the default compilation mode to `unchecked'. This makes all
the math operations unchecked (this is the default).
.I -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 producers)
and developers must follow to expose code to other programming
languages (CLS consumers).
.I -codepage:ID
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 specify utf-8 instead
of using the cryptic 65001 and "reset" restores the automatic handling of
code pages. These shorthands are not available on the Microsoft compiler.
.I \-define:SYMLIST, -d:SYMLIST
Defines the symbol listed by the semi-colon separated list SYMLIST
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
.I \-debug, \-debug+
Generate debugging information. To obtain stack traces with debugging
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.
.I \-debug-
Do not generate debugging information.
.I \-delaysign+
Only embed the strongname public key into the assembly. The actual
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 including [assembly: AssemblyDelaySign (true)]
in your source code. Compiler option takes precedence over the
.I \-delaysign-
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. Compiler option takes
precedence over the attributes.
.I \-doc:FILE
Extracts the C#/XML documentation from the source code and stores in in
the given FILE.
.I \-errorreport
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.
.I \-\-fatal
This is used for debugging the compiler. This makes the error emission
generate an exception that can be caught by a debugger.
.I \-filealign
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.
.I \-fullpaths
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.
.I \-keyfile:KEYFILE
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 containing only the
public key can be used with delaysign+. The option is equivalent to
including [assembly: AssemblyKeyFile ("KEYFILE")] in your source code.
Compiler option takes precedence over the attributes.
.I \-keycontainer:CONTAINER
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 [assembly:
AssemblyKeyName ("CONTAINER")] in your source code. Compiler option
takes precedence over the attributes.
.I \-langversion:TEXT
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 features.
The possible values are:
.ne 8
.I "Default"
Instruct compiler to use the latest version. Equivalent is to omit the
switch (this currently defaults to the C# 4.0 language specification).
.I "ISO-1"
Restrict compiler to use only first ISO standardized features.
The usage of features such as generics, static classes, anonymous
methods will lead to error.
.I "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.
.I "3"
Restrict the compiler to use only the features available in C# 3.0
(a superset of ISO-1 and ISO-2).
.I "4"
Restrict the compiler to use only the features available in C# 4.0
.I "experimental"
Enables unstable features from upcoming versions of the language.
Notice that this flag only restricts the language features available to
the programmer. A version of produced assemblies can be controlled using
Each path specified in the comma-separated list will direct the
compiler to look for libraries in that specified path.
Directs the compiler to look for libraries in the specified path.
Multiple paths can be provided by using the option multiple times.
.I \-main:CLASS
Tells the compiler which CLASS contains the entry point. Useful when
you are compiling several classes with a Main method.
.I \-nostdlib, -nostdlib+
Use this flag if you want to compile the core library. This makes the
compiler load its internal types from the assembly being compiled.
.I \-noconfig, \-noconfig+
Disables the default compiler configuration to be loaded. The
compiler by default has references to the system assemblies.
.I \-nowarn:WARNLIST
Makes the compiler ignore warnings specified in the comma-separated
.I -optimize, -optimize+, -optimize-
Controls compiler code generation optimizations on the code. Using -optimize or
-optimize+ will turn on optimizations, -optimize- will turn it off.
The default in mcs is to optimize-. The option can be mixed with -debug
but for the best debugging experience it is recommended leave the options off.
.I -out:FNAME, -o FNAME
Names the output file to be generated.
.I \-\-parse
Used for benchmarking. The compiler will only parse its input files.
.I \-pkg:package1[,packageN]
Reference assemblies for the given packages.
The compiler will invoke pkg-config --libs on the set of packages
specified on the command line to obtain libraries and directories to
compile the code.
This is typically used with third party components, like this:
$ mcs -pkg:gtk-sharp demo.cs
.ne 8
.I \-pkg:dotnet
This will instruct the compiler to reference the System.* libraries
available on a typical dotnet framework installation, notice that this
does not include all of the Mono libraries, only the System.* ones. This
is a convenient shortcut for those porting code.
.I \-platform:ARCH
Used to specify the target platform. The possible values are: anycpu,
anycpu32bitpreferred, arm, x86, x64 or itanium. The default option is
.I -resource:RESOURCE[,ID]
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.
.I -linkresource:RESOURCE[,ID]
Links to the specified RESOURCE. The optional ID can be used to give
a name to the linked resource.
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
.I -reference:ALIAS=ASSEMBLY
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 ASSEMBLY 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 ();
.I \-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'
.I \-sdk:VERSION
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
.NET version should the produced assembly be compatible with. When
custom value is specified mcs will try to find Base Class Libraries
in the mono installed location PREFIX/lib/mono/<value>.
.I \-\-shell
Starts up the compiler in interactive mode, providing a C# shell for
statements and expressions. A shortcut is to use the
.I csharp
command directly.
.I \-\-stacktrace
Generates a stack trace at the time the error is reported, useful for
debugging the compiler.
.I \-target:KIND, \-t:KIND
Used to specify the desired target. The possible values are: exe
(plain executable), winexe (Windows.Forms executable), library
(component libraries) and module (partial library).
.I \-\-timestamp
Another debugging flag. Used to display the times at various points
in the compilation process.
.I \-unsafe, -unsafe+
Enables compilation of unsafe code.
.I \-v
Debugging. Turns on verbose yacc parsing.
.I \-\-version
Shows the compiler version.
.I \-warnaserror, \-warnaserror+
All compilers warnings will be reported as errors.
.I \-warnaserror:W1,[Wn], -warnaserror+:W1,[Wn]
Treats one or more compiler warnings as errors.
.I \-warnaserror-:W1,[Wn]
Sets one or more compiler warnings to be always threated as warnings.
Becomes useful when used together with -warnaserror.
.I \-warn:LEVEL
Sets the warning level. 0 is the lowest warning level, and 4 is the
highest. The default is 4.
.I \-win32res:FILE
Specifies a Win32 resource file (.res) to be bundled into the
resulting assembly.
.I \-win32icon:FILE
Attaches the icon specified in FILE on the output into the resulting
.I \-\-
Use this to stop option parsing, and allow option-looking parameters
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
arguments 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
installation prefix under PREFIX/lib/mono/ called the PACKAGEBASE and the
defaults for mcs, gmcs and smcs are as follows:
.I mcs
References the PACKAGEBASE/1.0 directory
.I gmcs
References the PACKAGEBASE/2.0 directory
.I smcs
References the PACKAGEBASE/2.1 directory
Those are the only runtime profiles that exist. Although other
directories 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 foundation.
Software providers will distribute software that is installed relative
to the PACKAGEBASE directory. This is integrated into the
.I 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.
defines have a special meaning to the compiler.
By default calls to methods and properties in the
System.Diagnostics.Trace class are not generated unless the TRACE
symbol is defined (either through a "#define TRACE") in your source
code, or by using the
.I "--define TRACE"
in the command line.
By default calls to methods and properties in the
System.Diagnostics.Debug class are not generated unless the DEBUG
symbol is defined (either through a "#define DEBUG") in your source
code, or by using the
.I "--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
extension .mdb that contains the debugging information for the
generated assembly. This file is consumed by the Mono debugger (mdb).
If this variable is set, it contains a string in the form
"foreground,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:
.B 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, yellow,
blue, magenta, cyan, grey and white.
For example, you could set these variable from your shell:
You can disable the built-in color scheme by setting this variable to
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 platforms.
The Mono C# Compiler was written by Miguel de Icaza, Ravi Pratap,
Martin 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
( and Xamarin Inc ( is based on the
ECMA C# language standard available here:
The home page for the Mono C# compiler is at
Something went wrong with that request. Please try again.