✅ POSIX Compliance Progress

Comprehensive status of Rush Shell's compliance with IEEE Std 1003.1-2008 (POSIX sh)

90% Complete

90%

Overall Compliance

Built-in Commands

323+

Test Cases

1. Shell Command Language

1.1 Shell Introduction

✅ Interactive shell with prompt

✅ Script execution mode

✅ Command string execution (-c option)

✅ Real-time signal trap execution

✅ Signal handling (SIGINT, SIGTERM)

✅ Signal queue with bounded memory

1.2 Quoting

✅ Single quotes ('...')

✅ Double quotes ("...")

✅ Backslash escaping

✅ Quote removal

1.3 Token Recognition

✅ Tokenization of words, operators, newlines

✅ Reserved words (if, then, else, elif, fi, case, in, esac)

✅ Operators: | < > >> ; ;;

✅ Command substitution tokens ($(...) and `...`)

1.4 Reserved Words

✅ if, then, else, elif, fi

✅ case, in, esac

✅ while, until, for, do, done

✅ function

1.5 Parameters and Variables

✅ Variable assignment (VAR=value)

✅ Variable expansion ($VAR)

✅ Special parameters: $? $$ $0

✅ Positional parameters ($1, $2, ...)

✅ Special parameters: $* $@ $# $! $-

✅ Parameter expansion with modifiers

✅ Arithmetic expansion ($((...)))

1.6 Word Expansions

✅ Tilde expansion (~)

✅ Parameter expansion ($VAR)

✅ Command substitution ($(...) and `...`)

✅ Pathname expansion (globbing with *, ?, [...])

✅ Brace expansion ({a,b,c}, {1..5}, {a..z})

✅ Arithmetic expansion

1.7 Redirection

✅ Input redirection (<)

✅ Output redirection (>)

✅ Append redirection (>>)

✅ Here-document (<<)

✅ Here-string (<<<)

❌ File descriptor duplication (>&, <&)

❌ Redirections to specific file descriptors (2>, etc.)

1.8 Exit Status and Errors

✅ Exit status from commands

✅ Special parameter $? for last exit status

✅ Error reporting for syntax errors

2. Shell Commands

2.1 Simple Commands

✅ Simple command execution

✅ Built-in command execution

✅ External command execution with PATH search

2.2 Pipelines

✅ Pipeline execution (|)

✅ Pipeline exit status (last command's status)

2.3 Compound Commands

2.3.1 Grouping

❌ Subshell ((...))

❌ Command grouping {...}

2.3.2 Conditional Constructs

✅ if/elif/else/fi

✅ while/until loops

✅ for loops

2.3.3 Case Construct

✅ case/in/esac with glob patterns

✅ Pattern alternatives (|)

✅ Default case (*)

2.4 Functions

✅ Function definition and execution

✅ Local variables in functions

✅ Function introspection (declare -f)

3. Special Built-in Utilities

Implementation Status

20 Implemented 9 Missing

Required Special Built-ins

❌ break

❌ : (colon)

❌ continue

❌ eval

❌ exec

✅ exit

✅ export

❌ readonly

❌ return

❌ set

✅ shift

❌ times

✅ trap

❌ umask

✅ unset

❌ wait

Currently Implemented (20)

alias

declare

dirs

env

exit

export

help

popd

pushd

pwd

set_color_scheme

set_colors

set_condensed

shift

source

test

trap

unalias

unset

🎯 Implementation Priorities

High Priority (Core POSIX Features)

Redirections
- Here-documents (<<)
- File descriptor operations (2>, >&, etc.)
Missing Built-ins
- set (options and positional parameters)
- eval
- exec
- readonly, return, break, continue, etc.
Parameter Expansion
- Positional parameters ($1, $2, ...) - ✅ IMPLEMENTED
- Parameter modifiers (${VAR:-default}, etc.) - ✅ IMPLEMENTED
- Special parameters ($*, $@, $#) - ✅ IMPLEMENTED

Medium Priority

Job Control (optional)
- Background jobs (&)
- Job management (bg, fg, jobs, kill)

Low Priority

Advanced Features
- Command line editing enhancements
- History expansion (!!)
- Extended globbing

🧪 Testing Status

323+

Individual Test Cases

100%

Core Components Covered

Built-ins Tested

Test Coverage Areas

✅ Lexer tests (tokenization, expansion, quoting, arithmetic, parameter expansion)

✅ Parser tests (AST construction, control structures, if/elif/else, case statements)

✅ Executor tests (command execution, pipelines, redirections, built-in commands)

✅ Built-in tests (all implemented commands with comprehensive coverage)

✅ Integration tests (end-to-end scenarios, variable expansion, control structures)

✅ Arithmetic expansion tests (operators, precedence, variables, error handling)

✅ Parameter expansion tests (all modifiers, pattern matching, edge cases)

✅ Brace expansion tests (simple lists, ranges, nested braces, cartesian products)

✅ State management tests (variables, environment, positional parameters)

Areas Without Tests (Unimplemented Features)

❌ Advanced redirection scenarios (file descriptors)

❌ Missing built-in functionality (eval, exec, set, etc.)

❌ Job control features

📊 Compliance Breakdown

Category Breakdown

Basic Execution 95%

Control Structures 95%

Built-in Commands 69%

Expansions 98%

Redirections 75%

Job Control 0%

Advanced Features 40%

Certification Path

To achieve full POSIX compliance, focus on implementing the missing features listed in the priority sections above. Rush already has a solid foundation with:

✅ Comprehensive command execution and parsing
✅ Advanced expansion engines (parameter, arithmetic, brace)
✅ Full control structure support
✅ Extensive built-in command suite
✅ Thorough test coverage

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