forge debug


forge-debug - Debug a single smart contract as a script.


forge debug [options] path [args...]


Debugs a single smart contract located in the source file (path) as a script.

If multiple contracts are in the specified source file, you must pass --target-contract to specify what contract you want to run.


After the script is deployed to the internal EVM a call is made to a function with the signature setUp(), if present.

By default, the script is assumed to be contained in a function with the signature run(). If you wish to run a different function, pass --sig <SIGNATURE>.

The signature can be a fragment (<function name>(<types>)), or raw calldata.

If you pass a fragment, and the function has parameters, you can add the call parameters to the end of the command (args).


It is possible to run the script in a forked environment by passing --fork-url <URL>.

When the script is running in a forked environment, you can access all the state of the forked chain as you would if you had deployed the script. Cheatcodes are still available.

You can also specify a block number to fork from by passing --fork-block-number <BLOCK>. When forking from a specific block, the chain data is cached to ~/.foundry/cache. If you do not want to cache the chain data, pass --no-storage-caching.


It is possible to run the script in an interactive debugger. To start the debugger, pass --debug.

More information on the debugger can be found in the debugger chapter.


Debug Options

--target-contract contract_name
    The name of the contract you want to run

-s signature
--sig signature
    The signature of the function you want to call in the contract, or raw calldata. Default: run()

    Open the script in the debugger.

EVM Options

-f url
--rpc-url url
--fork-url url
    Fetch state over a remote endpoint instead of starting from an empty state.

    If you want to fetch state from a specific block number, see --fork-block-number.

--fork-block-number block
    Fetch state from a specific block number over a remote endpoint. See --fork-url.

--fork-retry-backoff <BACKOFF>
     Initial retry backoff on encountering errors.

    Explicitly disables the use of RPC caching.

    All storage slots are read entirely from the endpoint. See --fork-url.

    Verbosity of the EVM.

    Pass multiple times to increase the verbosity (e.g. -v, -vv, -vvv).

    Verbosity levels:
    - 2: Print logs for all tests
    - 3: Print execution traces for failing tests
    - 4: Print execution traces for all tests, and setup traces for failing tests
    - 5: Print execution and setup traces for all tests

--sender address
    The address which will be executing tests

--initial-balance balance
    The initial balance of deployed contracts

    Enables the FFI cheatcode

Executor Options

--base-fee <FEE>
--block-base-fee-per-gas <FEE>
    The base fee in a block (in wei).

--block-coinbase address
    The coinbase of the block.

--block-difficulty difficulty
    The block difficulty.

--block-gas-limit gas_limit
    The block gas limit.

--block-number block
    The block number.

--block-timestamp timestamp
    The timestamp of the block (in seconds).

--chain-id chain_id
    The chain ID.

--gas-limit gas_limit
    The block gas limit.

--gas-price gas_price
    The gas price (in wei).

--tx-origin address
    The transaction origin.

Cache Options

    Clear the cache and artifacts folder and recompile.

Linker Options

--libraries libraries
    Set pre-linked libraries.

    The parameter must be in the format <remapped path to lib>:<library name>:<address>, e.g. src/Contract.sol:Library:0x....

    Can also be set in your configuration file as libraries = ["<path>:<lib name>:<address>"].

Compiler Options

    Activate the Solidity optimizer.

--optimizer-runs runs
    The number of optimizer runs.

    Use the Yul intermediate representation compilation pipeline.

    How to treat revert and require reason strings.

--use solc_version
    Specify the solc version, or a path to a local solc, to build with.

    Valid values are in the format x.y.z, solc:x.y.z or path/to/solc.

    Do not access the network. Missing solc versions will not be installed.

    Do not auto-detect solc.

--ignored-error-codes error_codes
    Ignore solc warnings by error code. The parameter is a comma-separated list of error codes.

--extra-output selector
    Extra output to include in the contract's artifact.

    Example keys: abi, storageLayout, evm.assembly, ewasm, ir, ir-optimized, metadata.

    For a full description, see the Solidity docs.

--extra-output-files selector
    Extra output to write to separate files.

    Example keys: abi, storageLayout, evm.assembly, ewasm, ir, ir-optimized, metadata.

    For a full description, see the Solidity docs.

--evm-version version
    The target EVM version.

Project Options

    Generate build info files.

--build-info-path path
    Output path to directory that build info files will be written to.

--root path
    The project's root path. By default, this is the root directory of the current git repository, or the current working directory.

-C path
--contracts path
    The contracts source directory.
    Environment: DAPP_SRC

--lib-paths path
    The path to the library folder.

-R remappings
--remappings remappings
    The project's remappings.

    The parameter is a comma-separated list of remappings in the format <source>=<dest>.

--cache-path path
    The path to the compiler cache.

--config-path file
    Path to the config file.

    This is a convenience flag, and is the same as passing --contracts contracts --lib-paths node-modules.

-o path
--out path
    The project's artifacts directory.

    Suppress all output.

Common Options

    Prints help information.


  1. Execute the run() function in a contract:

    forge debug src/Contract.sol
  2. Open a script in the debugger:

    forge debug src/Contract.sol --debug
  3. Execute the foo() function in a contract:

    forge debug src/Contract.sol --sig "foo()"
  4. Execute a contract with a function that takes parameters:

    forge debug src/Contract.sol --sig "foo(string,uint256)" "hello" 100
  5. Execute a contract with raw calldata:

    forge debug src/Contract.sol --sig "0x..."


forge, forge test