WasmEdge command line tool (CLI)

After installing WasmEdge or starting the WasmEdge app dev Docker container, there are several ways to run compiled WebAssembly programs.

wasmedge

The wasmedge binary file is a command line interface (CLI) program that runs WebAssembly bytecode programs.

• If the WebAssembly program contains a main() function, wasmedge would execute it as a standalone program in the command mode.
• If the WebAssembly program contains one or more public functions, wasmedge could execute individual functions in the reactor mode.

Command line options

The options and flags for the wasmedge command are as follows.

1. (Optional) Statistics information:
   • Use --enable-time-measuring to show the execution time.
   • Use --enable-gas-measuring to show the amount of used gas.
   • Use --enable-instruction-count to display the number of executed instructions.
   • Or use --enable-all-statistics to enable all of the statistics options.
2. (Optional) Resource limitation:
   • Use --gas-limit to limit the execution cost.
   • Use --memory-page-limit to set the limitation of pages(as size of 64 KiB) in every memory instance.
3. (Optional) Reactor mode: use --reactor to enable reactor mode. In the reactor mode, wasmedge runs a specified function from the WebAssembly program.
   • WasmEdge will execute the function which name should be given in ARG[0].
   • If there’s exported function which names _initialize, the function will be executed with the empty parameter at first.
4. (Optional) Binding directories into WASI virtual filesystem.
   • Each directory can be specified as --dir guest_path:host_path.
5. (Optional) Environ variables.
   • Each variable can be specified as --env NAME=VALUE.
6. Wasm file (/path/to/wasm/file).
7. (Optional) Arguments.
   • In reactor mode, the first argument will be the function name, and the arguments after ARG[0] will be parameters of wasm function ARG[0].
   • In command mode, the arguments will be parameters of function _start. They are also known as command line arguments for a standalone program.

Once installed, you can review and run our examples.

wasmedgec

The wasmedgec binary file is a program to compile WebAssembly bytecode programs into native machine code (i.e., the AOT compiler). The compiled machine code could be stored in the original wasm file, and the wasmedge CLI will automatically choose to execute the native machine code whenever it is available.

The options and flags for the wasmedgec are as follows.

1. Input Wasm file(/path/to/input/wasm/file).
2. Output file name(/path/to/output/file).
   • By default, it will generate the universal Wasm binary format.
   • Users can still generate native binary only by specifying the .so, .dylib, or .dll extensions.

# This is slow
wasmedge app.wasm
# AOT compile
wasmedgec app.wasm app.wasm
# This is now MUCH faster
wasmedge app.wasm

On Linux systems, it could generate a so shared library file, which is then executed by the wasmedge CLI.

wasmedgec app.wasm app.so
wasmedge app.so