Bash Script Quality

Overview

Every bash script edit requires shellcheck validation. No exceptions for "simple" changes.

The Iron Law

ALWAYS run shellcheck after editing ANY bash script
ALWAYS iterate until ALL errors and warnings are fixed

Workflow

digraph bash_quality {
    "Edit bash script" [shape=box];
    "Run shellcheck" [shape=box];
    "Any issues?" [shape=diamond];
    "Fix ALL issues" [shape=box];
    "Done" [shape=doublecircle];

    "Edit bash script" -> "Run shellcheck";
    "Run shellcheck" -> "Any issues?";
    "Any issues?" -> "Done" [label="no"];
    "Any issues?" -> "Fix ALL issues" [label="yes"];
    "Fix ALL issues" -> "Run shellcheck";
}

After EVERY bash script edit:

1. Run shellcheck <file>
2. If errors exist, fix ALL of them (including pre-existing)
3. Run shellcheck again
4. Repeat until zero errors

Red Flags - STOP and Run Shellcheck

These thoughts mean you're rationalizing:

• "Just adding a comment"
• "Only changed a string"
• "Too simple to need validation"
• "File already worked before"
• "Shellcheck is too strict"
• "Only changed one line"
• "I'll run it after all edits"

All of these mean: Run shellcheck anyway. No exceptions.

Common Rationalizations

When NOT to Use

• Reading bash scripts (no edits)
• Non-bash file formats
• Files with explicit # shellcheck disable for valid reasons

Common Mistakes

Mistake: Adding comments/text before the shebang Fix: Shebang must be line 1. Comments go after.

Mistake: Running shellcheck only at the end of multiple edits Fix: Run after EVERY edit - errors compound and obscure root cause

Mistake: Ignoring warnings (only fixing errors) Fix: Fix ALL issues - warnings indicate real problems

Quick Reference

# Basic check
shellcheck script.sh

# Check with severity
shellcheck --severity=warning script.sh

# Disable specific check (in script)
# shellcheck disable=SC2086