BashSpark - A powerful C++ library for custom command execution.
BashSpark is a command-line tool inspired by the Bash shell that allows users to execute custom commands seamlessly and flexibly. It supports various command types and functionalities tailored for enhanced usability.

Key Features

Bash Inspiration: While it draws inspiration from the Bash shell, it introduces unique features and behaviors to enhance usability.
Custom Command Execution: Users can define and execute their own commands, enabling flexible scripting and automation.
Rich Functionality: Accommodates diverse user needs through various command types and execution options.

Bash-style Syntax Support

BashSpark supports a variety of Bash-style syntaxes including:

${VARIABLE_NAME}
${!VARIABLE_NAME}
$(command)
function function_name {...}

Note: Does not recognize semicolons or newlines generated by expansion. Example: $cmd where cmd="echo -n 1; echo -n 2" outputs 1; echo -n 2, not 12.

Unique Capabilities

Interprets escaped characters (e.g., \n for newline, \t for tab).
Supports Unicode code points:
- \x for ASCII
- \u for UTF-16
- \U for UTF-32
Returns shell_status::SHELL_ERROR_BAD_ENCODING for invalid code points.

Different Behavior from Bash

No requirement for spaces around '(', '[', '{', '}', ']' and ')'.
Both ( and [ are always interpreted, e.g., "echo }" works while "echo \\}" works in both.
Supports empty commands with valid syntax like ";;;".
Does not support improved test syntax [[...]].
Normal tests support ||, && and parentheses (...).
Arithmetic using (()) is not supported; use the math command instead.
Variable assignments using variable=value are not supported; use setenv and setvar commands.
Function definition syntax function_name(){...} is not supported; use fcall function_name <args>.

Command Management

Commands are instantiated from the bs::command class and managed within the shell to ensure safe and reliable command execution by preventing security holes and handling errors gracefully.

Shell Depth

The parser has a limit for depth set by std::size_t bs::shell::MAX_DEPTH, defaulting to 16. Users can modify this value and rebuild the project if necessary. The following conditions increase depth:

Parsing subblocks like "(...)" and "{...}"
Parsing subcommands like "$(...)"
Command eval (new shell starts a new depth).
Keywords like "if", "elif", "for", "while", "until".

Parsing variables ${...}, tests [...], and keywords like "then", "fi", "else", "do", "done" do not increase depth.

Known Issues

Current implementation attempts to prevent SIGSEGV. The shell execution does not throw exceptions except for std::bad_alloc or exceptions from provided streams. All errors listed on bs::shell_status are notified through stderr with the last command error code, including syntax errors and depth limit errors.

Other limitations:

Shell arguments are restricted to 19 digits due to std::uint64_t range.