Bash Linux Patterns

Essential patterns for Bash on Linux/macOS.

1. Operator Syntax

Chaining Commands

2. File Operations

Essential Commands

3. Process Management

4. Text Processing

Core Tools

5. Environment Variables

6. Network

7. Script Template

#!/bin/bash
set -euo pipefail  # Exit on error, undefined var, pipe fail

# Colors (optional)
RED='\033[0;31m'
GREEN='\033[0;32m'
NC='\033[0m'

# Script directory
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

# Functions
log_info() { echo -e "${GREEN}[INFO]${NC} $1"; }
log_error() { echo -e "${RED}[ERROR]${NC} $1" >&2; }

# Main
main() {
    log_info "Starting..."
    # Your logic here
    log_info "Done!"
}

main "$@"

8. Common Patterns

Check if command exists

if command -v node &> /dev/null; then
    echo "Node is installed"
fi

Default variable value

NAME=${1:-"default_value"}

Read file line by line

while IFS= read -r line; do
    echo "$line"
done < file.txt

Loop over files

for file in *.js; do
    echo "Processing $file"
done

9. Differences from PowerShell

10. Error Handling

Set options

set -e          # Exit on error
set -u          # Exit on undefined variable
set -o pipefail # Exit on pipe failure
set -x          # Debug only with non-secret inputs; prints expanded arguments

Trap for cleanup

cleanup() {
    echo "Cleaning up..."
    rm -f /tmp/tempfile
}
trap cleanup EXIT

Remember: Bash is text-based. Use && for success chains and quote variables. set -e has conditional/pipeline exceptions; explicitly check consequential operations and never infer complete safety from shell flags.

When to Use

This skill is applicable to execute the workflow or actions described in the overview.

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.