[Dragonshadow]

I've looked through all the sp files, the inc files, etc, and I can't find its source code to see how it works.

Anyone know where it is?

[Greyscale]

It's just a wrapper around SetConVarString.

Uses FindConVar on the entered cvar, if it returns INVALID_HANDLE it says "couldn't find cvar" and then set's it to the value SetConVarString and replys to the command if it found the cvar.

[DJ Tsunami]

If you want to know how SetConVarString works you'll have to look at the C++ source code, which is available on http://hg.alliedmods.net.

[Dragonshadow]

I don't understand c++ one bit xD
but thanks, I just wanted to know how it worked so I could manually set cvars through a plugin without it notifying on every cvar.

[Greyscale]

In that case you're looking for:

/**
 * @section Flags for console commands and console variables.  The descriptions 
 * for each constant come directly from the Source SDK.
 */
#define FCVAR_NONE				0		/**< The default, no flags at all */
#define FCVAR_UNREGISTERED		(1<<0)	/**< If this is set, don't add to linked list, etc. */
#define FCVAR_LAUNCHER			(1<<1)	/**< Defined by launcher. */
#define FCVAR_GAMEDLL			(1<<2)	/**< Defined by the game DLL. */
#define FCVAR_CLIENTDLL			(1<<3)	/**< Defined by the client DLL. */
#define FCVAR_MATERIAL_SYSTEM	(1<<4)	/**< Defined by the material system. */
#define FCVAR_PROTECTED			(1<<5)	/**< It's a server cvar, but we don't send the data since it's a password, etc. Sends 1 if it's not bland/zero, 0 otherwise as value. */
#define FCVAR_SPONLY			(1<<6)	/**< This cvar cannot be changed by clients connected to a multiplayer server. */
#define	FCVAR_ARCHIVE			(1<<7)	/**< Set to cause it to be saved to vars.rc */
#define	FCVAR_NOTIFY			(1<<8)	/**< Notifies players when changed. */
#define	FCVAR_USERINFO			(1<<9)	/**< Changes the client's info string. */
#define FCVAR_PRINTABLEONLY		(1<<10)	/**< This cvar's string cannot contain unprintable characters (e.g., used for player name, etc.) */
#define FCVAR_UNLOGGED			(1<<11)	/**< If this is a FCVAR_SERVER, don't log changes to the log file / console if we are creating a log */
#define FCVAR_NEVER_AS_STRING	(1<<12)	/**< Never try to print that cvar. */
#define FCVAR_REPLICATED		(1<<13)	/**< Server setting enforced on clients. */
#define FCVAR_CHEAT				(1<<14)	/**< Only useable in singleplayer / debug / multiplayer & sv_cheats */
#define FCVAR_STUDIORENDER		(1<<15)	/**< Defined by the studiorender system. */
#define FCVAR_DEMO				(1<<16)	/**< Record this cvar when starting a demo file. */
#define FCVAR_DONTRECORD		(1<<17)	/**< Don't record these command in demo files. */
#define FCVAR_PLUGIN			(1<<18)	/**< Defined by a 3rd party plugin. */
#define FCVAR_DATACACHE			(1<<19)	/**< Defined by the datacache system. */
#define FCVAR_TOOLSYSTEM		(1<<20)	/**< Defined by an IToolSystem library */
#define FCVAR_FILESYSTEM		(1<<21)	/**< Defined by the file system. */
#define FCVAR_NOT_CONNECTED		(1<<22)	/**< Cvar cannot be changed by a client that is connected to a server. */
#define FCVAR_SOUNDSYSTEM		(1<<23)	/**< Defined by the soundsystem library. */
#define FCVAR_ARCHIVE_XBOX		(1<<24)	/**< Cvar written to config.cfg on the Xbox. */
#define FCVAR_INPUTSYSTEM		(1<<25)	/**< Defined by the inputsystem DLL. */
#define FCVAR_NETWORKSYSTEM		(1<<26)	/**< Defined by the network system. */
#define FCVAR_VPHYSICS			(1<<27)	/**< Defined by vphysics. */

/**
 * Returns the bitstring of flags on a console variable.
 *
 * @param convar		Handle to the convar.
 * @return				A bitstring containing the FCVAR_* flags that are enabled.
 * @error				Invalid or corrupt Handle.
 */
native GetConVarFlags(Handle:convar);

/**
 * Sets the bitstring of flags on a console variable.
 *
 * @param convar		Handle to the convar.
 * @param flags			A bitstring containing the FCVAR_* flags to enable.
 * @noreturn
 * @error				Invalid or corrupt Handle.
 */
native SetConVarFlags(Handle:convar, flags);

Ex:

new cvarflags = GetConVarFlags(MYCVARHANDLE);  Get the handle of a named cvar with FindConVar, or if it's your own cvar you should store the handle in a global variable.
cvarflags |= ~FCVAR_NOTIFY;  // To be honest, I'm not sure if this is right, can someone verify?  I suck with bitwise operations.
SetConVarFlags(MYCVARHANDLE, cvarflags); // Reset the flags

[J-Factor]

Originally Posted by Greyscale cvarflags |= ~FCVAR_NOTIFY; // To be honest, I'm not sure if this is right, can someone verify? I suck with bitwise operations.

It should be:

cvarflags &= ~FCVAR_NOTIFY;

If you want to turn something on, use an OR mask (|=).

If you want to turn something off, use an AND mask (&=).