Learn-skills.dev shell-scripts

Use when writing or reviewing Bash scripts and shell snippets, especially for shebang selection, quoting, parameter expansion ("${VAR}" style), test expressions ([ ] vs [[ ]]), ShellCheck-guided fixes, and portability decisions across POSIX sh, Bash, and zsh compatibility targets.

install

source · Clone the upstream repo

git clone https://github.com/NeverSight/learn-skills.dev

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/NeverSight/learn-skills.dev "$T" && mkdir -p ~/.claude/skills && cp -r "$T/data/skills-md/ahgraber/skills/shell-scripts" ~/.claude/skills/neversight-learn-skills-dev-shell-scripts && rm -rf "$T"

manifest: data/skills-md/ahgraber/skills/shell-scripts/SKILL.md

source content

Writing Shell Scripts

Overview

Write shell code with an explicit portability target first, then apply strict quoting and a bounded ShellCheck remediation loop. Default to Bash readability and safety; switch to POSIX-only mode when the user asks for strict portability.

Invocation Notice

Inform the user when this skill is being invoked by name:
```
shell-scripts
```
.

When to Use

Creating or refactoring Bash scripts.
Reviewing shell snippets for correctness and safety.
Standardizing shebangs, quoting, variable expansion style, and test syntax.
Deciding between POSIX-compliant syntax and Bash-specific features.
Improving compatibility with zsh environments.

When NOT to use:

The task is strictly
```
fish
```
,
```
powershell
```
, or Windows batch.
The user explicitly wants pure POSIX
```
sh
```
and no Bash features (use POSIX mode from
```
references/compatibility-matrix.md
```
).

Workflow

Select the target mode from
```
references/compatibility-matrix.md
```
: POSIX strict, Bash-first, or Bash-with-zsh-compatibility.

Start from

assets/script-template.sh

or pull focused snippets from:

```
assets/usage-template.txt
```
```
assets/logging-template.sh
```
```
assets/getopts-template.sh
```

Apply style defaults:
- Shebang per target mode.
- Prefer
```
${VAR}
```
  expansion form for clarity.
- Quote expansions unless intentionally relying on shell splitting/pattern behavior.
- In Bash mode, prefer arrays for argument vectors and list handling; in POSIX mode, avoid arrays.
- Use
```
[[ ... ]]
```
  for Bash conditionals; use
```
[ ... ]
```
  when POSIX compatibility is required.
- For command execution, verify resolution with
```
command -v
```
  /
```
type -a
```
  when shadowing is possible.

Validate syntax and lint:

```
bash -n path/to/script.sh
```
```
shellcheck -x path/to/script.sh
```
(if available)

ShellCheck remediation budget:
- Do at most two fix rounds.
- Round 1: fix correctness/safety and high-confidence issues.
- Round 2: re-run and fix remaining practical issues.
- Stop after round 2 and report remaining findings with rationale.

For advanced logic and portability traps, load:

```
references/advanced-patterns.md
```

references/command-resolution-and-os-portability.md

```
references/quoting-and-expansion.md
```
```
references/tests-and-conditionals.md
```
```
references/shellcheck-workflow.md
```

Output

A script (or patch) with explicit target shell assumptions.
Consistent quoting/expansion style and conditional style.
ShellCheck findings reduced within the two-pass budget, with unresolved items documented.

References

```
references/compatibility-matrix.md
```
```
references/quoting-and-expansion.md
```
```
references/tests-and-conditionals.md
```
```
references/shellcheck-workflow.md
```
```
references/advanced-patterns.md
```

references/command-resolution-and-os-portability.md

```
references/shellcheck-codes.md
```