Posix shell validator

Skill a5c-ai/babysitter/library/specializations/cli-mcp-development/skills/posix-shell-validator

Babysitter enforces obedience on agentic workforces and enables them to manage extremely complex tasks and workflows through deterministic, hallucination-free self-orchestration

Install

npx -y skills add a5c-ai/babysitter --skill posix-shell-validator

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

What its author says it does

Copied from the file, not written here

Validate scripts for POSIX compliance with portability checks, bashism detection, and cross-platform compatibility.

SKILL.md

3.2 KB, as published. Nobody here has run it

POSIX Shell Validator

Validate scripts for POSIX compliance and portability.

Capabilities

Detect bashisms in shell scripts
Validate POSIX compliance
Check cross-platform compatibility
Identify non-portable constructs
Generate compliance reports
Suggest portable alternatives

Usage

Invoke this skill when you need to:

Validate scripts for POSIX compliance
Detect bashisms before deployment
Ensure cross-platform compatibility
Generate compliance reports

Common Bashisms to Avoid

# Bashism → POSIX Alternative

# Arrays
arr=(a b c)           # Use: set -- a b c; or newline-separated
${arr[0]}             # Use: $1 (after set --)

# [[ ]] test
[[ $x == y ]]         # Use: [ "$x" = "y" ]
[[ $x =~ regex ]]     # Use: case or expr

# String substitution
${var/old/new}        # Use: $(echo "$var" | sed 's/old/new/')
${var,,}              # Use: $(echo "$var" | tr '[:upper:]' '[:lower:]')
${var^^}              # Use: $(echo "$var" | tr '[:lower:]' '[:upper:]')

# Arithmetic
((x++))               # Use: x=$((x + 1))
$((x**2))             # Use: $(expr $x \* $x) or awk

# Here strings
cat <<< "$var"        # Use: echo "$var" | cat

# Process substitution
diff <(cmd1) <(cmd2)  # Use: temp files

# Brace expansion
{1..10}               # Use: seq 1 10
file.{txt,md}         # Use: file.txt file.md

# Local variables
local var             # Use: var= (function-scoped in many shells)

# Source
source file           # Use: . file

# Function syntax
function name { }     # Use: name() { }

Validation Script

#!/bin/sh
# POSIX compliance validator

check_file() {
    file="$1"
    errors=0

    # Check shebang
    head -1 "$file" | grep -q '^#!/bin/bash' && {
        echo "WARNING: $file uses bash shebang"
        errors=$((errors + 1))
    }

    # Check for bashisms
    bashisms='
        \[\[
        \(\(
        \$\{[^}]*//
        \$\{[^}]*,,
        \$\{[^}]*\^\^
        \$\{[^}]*:[-+=?][^}]*\}
        <<<
        <\(
        >\(
        \{[0-9]+\.\.[0-9]+\}
        function[[:space:]]+[a-zA-Z_]
        source[[:space:]]
        declare[[:space:]]
        local[[:space:]]
        readonly[[:space:]]
    '

    for pattern in $bashisms; do
        if grep -En "$pattern" "$file" 2>/dev/null; then
            echo "BASHISM: $file contains: $pattern"
            errors=$((errors + 1))
        fi
    done

    return $errors
}

# Run checkbashisms if available
if command -v checkbashisms >/dev/null 2>&1; then
    checkbashisms -f "$1"
else
    check_file "$1"
fi

Target Processes

shell-script-development
cross-platform-cli-compatibility
cli-unit-integration-testing