Build Systems – Basics


You can use build systems to run files through external programs and see any generated output, all without leaving Sublime Text.


We use the term build in a broad sense. A build system doesn’t need to generate a compiled executable—it could simply format code, run an interpreter, etc.

Parts of a Build System

Simple build systems only require a .sublime-build file. More advanced build systems may optionally consist of up to three parts:

  • a .sublime-build file (configuration data in JSON format);
  • optionally, a custom Sublime Text command (Python code) driving the build process;
  • optionally, an external executable file (script or binary file).

File Format of .sublime-build Files

Format JSON (with comments)
Extension .sublime-build
Name Any
Location Any under Packages
Content Predefined items and, optionally, arbitrary user-defined items

A .sublime-build file contains configuration data as a JSON object and specifies switches, options and environmental data. Each .sublime-build file is normally associated with a specific scope corresponding to a file type (for example, source.python).

The file name represents the name of the build system and will be displayed whenever you can select a build system.


    "cmd": ["python", "-u", "$file"],
    "file_regex": "^[ ]*File \"(...*?)\", line ([0-9]*)",
    "selector": "source.python"

The Sublime Text Command Used in A Build System

When you run the default build task in Sublime Text (Ctrl+B), a Sublime Text command receives the configuration data specified in the .sublime-build file. This command then builds the files. Often, it calls an external program. By default, the command used in build systems is exec, but it can be overridden.

Overriding the Default Command for Build Systems

By default, build systems use the exec command implemented by Packages/Default/ This command simply forwards configuration data to an external program and runs it asynchronously.

Using the target option in a .build-system file, it’s possible to override the exec command. See Target Command Arguments for details.

Calling External Programs

A build system may call an external program to process files. The external program may be a custom shell script, a standard utility like make or tidy, etc. Usually, the external program receives paths to files or directories, along with switches and options that configure its behavior.


Build systems can but don’t need to call external programs—a build system could be implemented entirely as a Sublime Text command.