An OCaml-based implementation of Bash mini-language including a parser, an interpreter, and a REPL.

The library uses dune as a build system. Run the following command for it to be built:

dune build

REPL is ready to be run as an executable after it is built:

dune exec ./REPL.exe

Contents:

• The library itself is available in lib
• Usage demos are available in demos
• REPL is in REPL.ml

Currently miniBash supports the following features:

• Quoting
• Commands
  • Simple commands
  • Pipelines (concurrent execution is not supported)
  • Command lists (&& and ||)
  • Compound commands
    • while
    • for (two syntactic variants)
    • if
    • case
    • ((...))
    • {...}
• Functions (with recursion)
• Variables and parameters
  • Out of positional and special parameters only numerical positional parameters are supported
• Expansions (expansions are not allowed to be nested)
  • Brace expansion
  • Shell parameter expansion
  • Command substitution (in two forms, but both of them behave in the same new-fashioned way)
  • Word splitting (partial; on <space>, <tab> and <newline> only)
  • Arithmetical expansion (with variables)
  • Filename expansion
• Pattern matching
• Redirections (<, >, >>, <&, >&)
  • No checking for input/output availability
  • No descriptors from variables
• Arrays
  • Indexed: name=(value1 value2 value3 ...)
  • Associative: name=(key1=value1 key2=value2 ...)
• External executables
  • An executable is first attemted to be interpreted as a miniBash script, and if this fails then it is run via a system's shell

The implemented miniBash REPL is a mix of a traditional REPL and a command-line shell:

• after each command is executed its return code is printed
• commands do not need to be terminated with any special sequence to be executed

Example:

        MiniBash REPL
- To run a command, type it and press Enter
- To stop typing a multiline command prematurely, enter an empty line
- To exit REPL type `exit` or press Ctrl-D
$ echo "Hello $(echo "world!")"
Hello world!
return code: 0
$ for i in a b c; do
> echo $i
> done
a
b
c
return code: 0
$