CLI Usage


Scribble accepts normal Solidity files and has 3 output modes:

  1. In flat mode, all the dependencies of the target Solidity file(s) are bunched up and emitted as one giant blob of Solidity that can be compiled or directly submitted to MythX.

  2. In files mode, for each file foo.sol containing contracts with scribble annotations, Scribble emits a foo.instrumented.sol in the same directory and leaves the original unchanged. Note that scribble may instrument files that are not specified on the command line, but are reachable by a chain of imports.

  3. In json mode, Scribble behaves similarly to flat mode, in that it first flattens all the files necessary to compile the target into one flat Solidity blob. Afterwards, it runs solc on that flat solidity blob and outputs the slightly modified standard JSON output of the used compiler version.

Quick recipes

We provide examples for the most common use cases. For all examples assume we have the following 2 solidity files in the current directory:


contract Base {


import "Base.sol";
contract Foo is Base {
/// #if_succeeds {:msg "P1"} y == x + 1;
function inc(uint x) public pure returns (uint y) {
return x+1;

Emitting a flat instrumented file

If we want to instrument Foo.sol (and any required imports) and emit it all into a single Foo.flat.sol we can run:

scribble Foo.sol --output-mode flat --output Foo.flat.sol

Note that both the input and the output can be -- which would make Scribble work with stdin/stdout. The below command uses stdin/stdout to do the same thing as the previous command:

cat Foo.sol | scribble -- --output-mode flat --output -- > Foo.flat.sol

Instrumenting files in-place

The files mode is more involved and is intended for interoperability with various user testing and deployment environments. To instrument Foo.sol and Base.sol in-place we run:

scribble Foo.sol --output-mode files

After running this we will have 2 new files in the directory - Foo.instrumented.sol and __scribble_ReentrancyUtils.sol. Foo.instrumented.solis the instrumented version of Foo.sol, and __scribble_ReentrancyUtils.sol contains a helper contract.

Note that the instrumented Foo.instrumented.sol still imports the original Base.sol. To actually use the instrumented files in this mode, you have to swap them with the originals, before compiling/testing/deploying. You can do so manually, or automatically with the the --arm and --disarm options to scribble (more details here).

Emitting an instrumented JSON artifact

Emitting an instrumented JSON artifact is almost the same as running in flat-mode:

scribble Foo.sol --output-mode json --output Foo.flat.json

The generated Foo.flat.json contains the target solidity files and their dependencies, compiled in the slightly modified standard JSON output of the used compiler version.

Command line options reference

-h, --help Print help message
-v, --version Print package version
-q, --quiet Don't output anything to stderr
-i, --input-mode string Input mode. Either 'source' or 'json'. When 'source' is specified, input
assumed to be a raw Solidity source code. When 'json' is specified, input
assumed to be a Solc output JSON artifact.
-m, --output-mode string Output mode. Either 'flat', 'files' or 'json'. When 'flat' is specified,
output all instrumented contracts toghether. When 'files' is specified, for
every file Foo.sol that contains an annotated contract emit a
Foo.sol.instrumetned with the instrumented contract. When 'json' is
specified, a JSON object including the original sources, the flattened
bytecode, and a map from property IDs to their locations.
-k, --keep-instrumented Keep instrumented files after disarming.
-o, --output string When the output mode if 'flat' or 'json' specifies where to dump the
flattened contracts. Either a path to a file, or '--' for stdout.
--utils-output-path string Path to a folder where the ReentrancyUtils.sol contract should be emitted.
This option is required with '--mode files' and ignore otherwise.
--property-map-file string If specified, output the property map (in JSON format) in the specified file.
--path-remapping string Path remapping input for Solc. A semicolon separate list of remappings
--compiler-version string If given, specifies the exact compiler version to use
--no-assert If specified execution will not halt when an invariant is violated (only an
event will be emitted).
--filter-type string If specified instrumentation will happen only for annotations, whose types
are matching supplied regular expression.
--filter-message string If specified instrumentation will happen only for annotations, whose messages
are matching supplied regular expression.
--arm When instrumenting files in-place ('--output-mode files') also swap the
instrumented files with the original.
--disarm Find all dependencies of the traget that have been swapped with their
instrumented version (all foo.sol s.t. there is a foo.sol.instrumented and
foo.sol.original) and swap them back for the original.
--debug-events When specified for every failure an additional debug event with values of
variables in the failing predicate is emitted.
--user-assert-mode string Describe how scribble signals user assertion failures to Myhtril/Harvey. Must
be either 'log' or 'mstore'. See wiki for more details.
--solFiles string[] List of solidity files to instrument. Either a path to a file, or '--' for

Important caveats

  1. --output doesn't have any effect with --output-mode files.

  2. --utils-output-path allows to specify a different directory for the helper __scribble_ReentrancyUtils.sol file. It only works with --output-mode files. It doesn't have any effect with --output-mode flat.

  3. If --no-assert is omitted, then there is an assert(false) emitted in the instrumented code every time an invariant is violated. For longer-running fuzzing campaigns, it may be useful to keep running the code even after a property is violated. In those cases only an AssertionFailed(string) event is emitted, which can be caught by tools such as MythX/Mythril/Harvey.

  4. You can't pass standard json with missing sources to scribble.