linux

name	linux
description	Bash/Linux terminal patterns. Critical commands, piping, error handling, scripting. Use when working on macOS, Linux, or any system with Bash/Zsh.

Bash Linux Patterns

Essential patterns for Bash on Linux/macOS. Load shell-strategy.md file before execution.

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1. Operator Syntax

Chaining Commands

Operator	Meaning	Example
;	Run sequentially	cmd1; cmd2
&&	Run if previous succeeded	pnpm install && pnpm run dev
||	Run if previous failed	pnpm test || echo "Tests failed"
|	Pipe output	ls | rg ".js"

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2. File Operations

Essential Commands

Task	Command
List all	eza --all --color=never --icons=never --long --no-time --no-user --group-directories-first
Find files	fd . -e log ~/.local/share/opencode
File content	cat file.txt
First N lines	head -n 20 file.txt
Last N lines	tail -n 20 file.txt
Follow log	tail -f log.txt
Search in files	rg -iL "regex" *.js
File size	du -sh *
Disk usage	df -h

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3. Process Management

Task	Command
List processes	ps aux
Find by name	ps aux | rg -iN node
Kill by PID	kill -9 <PID>
Find port user	lsof -i :3000
Kill port	kill -9 $(lsof -t -i :3000)
Background	pnpm dev &
Jobs	jobs -l
Bring to front	fg %1

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4. Text Processing

Core Tools

Tool	Purpose	Example
rg	Search	rg "TODO" src/
sed	Replace	sed -i 's|old|new|g' file.txt
awk	Extract columns	awk -F ' ' '{print $1}' file.txt
cut	Cut fields	cut -d',' -f1 data.csv
sort	Sort lines	sort -u file.txt
uniq	Unique lines	sort file.txt | uniq -c
wc	Count	wc -l file.txt

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5. Environment Variables

Task	Command
View all (not secure)	env or printenv
View all (secure)	env | rg -v 'api|key|secret' or printenv | rg -v 'api|key|secret'
View one	echo $PATH
Set temporary	export VAR="value"
Set in script	VAR="value" command
Add to PATH	export PATH="$PATH:/new/path"

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6. Network

Task	Command
Download	wget https://example.com/file
API request	curl -X GET https://api.example.com
POST JSON	curl -X POST -H "Content-Type: application/json" -d '{"key":"value"}' URL
Check port	nc -zv localhost 3000
Network info	ip addr or ifconfig

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7. Script Template

Use mkscript -f script.sh for a standard bash script in the selected path, mkscript -t to make a temporary script (lives in /tmp)

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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

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9. Differences from PowerShell

Task	PowerShell	Bash
List files	Get-ChildItem	ls -la
Find files	Get-ChildItem -Recurse	find . -type f
Environment	$env:VAR	$VAR
String concat	"$a$b"	"$a$b" (same)
Null check	if ($x)	if [[ -n "${x}" ]]
Pipeline	Object-based	Text-based

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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: print commands
set +x          # Unset debug mode

Trap for cleanup

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

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Remember: Bash is text-based. Use && for success chains, set -e for safety, and quote your variables!

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.