Agent skill

Ninja

by mohitmishra786 in mohitmishra786/low-level-dev-skills

Ninja build system skill. An agent skill from mohitmishra786/low-level-dev-skills.

MITAuto-check passedDevelopment

Install Ninja

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills ninja --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/build-systems/ninja .claude/skills/ninja && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "ninja" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/build-systems/ninja into .claude/skills/ninja/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ninja", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/build-systems/ninja

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills ninja --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/build-systems/ninja .agents/skills/ninja && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "ninja" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/build-systems/ninja into .agents/skills/ninja/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ninja", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills ninja --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/build-systems/ninja .cursor/skills/ninja && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "ninja" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/build-systems/ninja into .cursor/skills/ninja/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ninja", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/mohitmishra786/low-level-dev-skills.git --path skills/build-systems/ninja

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills ninja --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/build-systems/ninja .gemini/skills/ninja && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "ninja" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/build-systems/ninja into .gemini/skills/ninja/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ninja", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills ninja

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/build-systems/ninja .github/skills/ninja && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "ninja" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/build-systems/ninja into .github/skills/ninja/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ninja", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills ninja --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/build-systems/ninja .opencode/skills/ninja && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "ninja" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/build-systems/ninja into .opencode/skills/ninja/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ninja", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: ninja
GitHub stars: 253
Token cost: ~1.2k tokens
SKILL.md length: 323 words
Files: 2 (incl. references)
Skills in repo: 138
Repo updated: Jun 27, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Ninja build system skill. An agent skill from mohitmishra786/low-level-dev-skills.

Works in 8 steps: Ninja as a CMake generator → Verbose output and diagnostics → Common Ninja flags → …
Diagnosing Ninja build failures
SKILL.md covers Purpose, Triggers, Workflow and Related skills
Calls cmake

What it does

Ninja is an agent skill from mohitmishra786/low-level-dev-skills. Ninja build system skill. Use when diagnosing Ninja build failures, understanding Ninja's role as a low-level build executor generated by CMake or other meta-build systems, tuning parallelism, interpreting Ninja output, or working with build.ninja files. Activates on queries about ninja errors, ninja parallelism, ninja verbose output, build.ninja format, or ninja as a CMake generator.

Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/cheatsheet.md`).

It sits in Development. It works with C++. The repository describes itself as: A curated suite of AI agent skills for systems and low-level programming with C/C++, Rust, and Zig toolchains, covering compilers, debuggers, profilers, build systems…. The licence is MIT.

When your agent uses it

Diagnosing Ninja build failures
Understanding Ninjas role as a low-level build executor generated by CMake
Other meta-build systems
Tuning parallelism

Example prompts

“/ninja”

Workflow steps

8 steps, taken from the step headings in SKILL.md.

Ninja as a CMake generator
Verbose output and diagnostics
Common Ninja flags
Cleaning
compile_commands.json
build.ninja format (reference)
Ninja sub-tools
Common issues

What it can do on your machine

Read from SKILL.md and the folder at commit bdc5847. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- cmake
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Ninja loads about 1.2k tokens when it runs, and up to ~2.6k if it reads all its reference files. Until then it costs about 98 tokens; SKILL.md has 323 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~98
When it runs · the whole SKILL.md, loaded when a task matches: ~1.2k
With references · SKILL.md plus every file in references/, read only if the agent opens them: ~2.6k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from mohitmishra786/low-level-dev-skills at commit bdc5847, republished under its MIT licence (© mohitmishra786). 323 words, ~1,153 tokens.

Download SKILL.mdSave it as .claude/skills/ninja/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.

name: ninja
description: Ninja build system skill. Use when diagnosing Ninja build failures, understanding Ninja's role as a low-level build executor generated by CMake or other meta-build systems, tuning parallelism, interpreting Ninja output, or working with build.ninja files. Activates on queries about ninja errors, ninja parallelism, ninja verbose output, build.ninja format, or ninja as a CMake generator.
user-invocable: true
triggers: ninja build failure, ninja parallelism tuning, cmake ninja generator, interpret ninja output, build.ninja file format, ninja verbose output, ninja as cmake…

Ninja

Purpose

Guide agents through Ninja as a build executor: diagnosing failures, controlling parallelism, generating from CMake, and understanding the .ninja file format when needed.

Triggers

"Ninja is failing — how do I get more output?"
"How do I use Ninja with CMake?"
"How many parallel jobs does Ninja use?"
"How do I add a custom build step in Ninja?"
"What is a build.ninja file?"

Workflow

1. Ninja as a CMake generator

The most common use of Ninja is as the build executor for CMake:

bash

# Configure with Ninja
cmake -S . -B build -G Ninja
cmake --build build                    # uses ninja internally

# Or invoke ninja directly
cd build && ninja

# Specify parallelism
ninja -j4
ninja -j$(nproc)

# Build specific target
ninja myapp
ninja install

CMake also supports Ninja Multi-Config:

bash

cmake -S . -B build -G "Ninja Multi-Config"
cmake --build build --config Release
cmake --build build --config Debug

2. Verbose output and diagnostics

bash

# Show full commands (not just [CC] foo.c)
ninja -v

# Dry run (show what would be built)
ninja -n

# Show why a target needs rebuilding
ninja -d explain myapp

# Print all targets
ninja -t targets all

# Print targets grouped by rule
ninja -t targets rule cc

# Dependency graph (graphviz)
ninja -t graph myapp | dot -Tsvg -o deps.svg

3. Common Ninja flags

Flag	Effect
`-j N`	Parallel jobs (default: CPUs + 2)
`-l N`	Don't start new jobs if load average > N
`-k N`	Keep going after N failures (default 1)
`-v`	Verbose: show full command lines
`-n`	Dry run
`-C dir`	Change to `dir` before doing anything
`-t tool`	Run a sub-tool (`clean`, `query`, `targets`, `graph`, `compdb`)

4. Cleaning

bash

ninja -t clean          # remove build outputs
ninja -t clean -g       # also remove generated files

Or via CMake:

bash

cmake --build build --target clean

5. compile_commands.json

Ninja (via CMake) can generate a compile_commands.json for IDE integration and clang-tidy:

bash

cmake -S . -B build -G Ninja -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
ln -sf build/compile_commands.json .

6. build.ninja format (reference)

Rarely hand-written, but useful to understand for debugging:

ninja

# Variable
cflags = -Wall -O2

# Rule
rule cc
  command = gcc $cflags -c $in -o $out
  description = CC $in

# Build edge
build foo.o: cc foo.c

# Phony target
build all: phony foo.o

# Default target
default all

Key concepts:

rule: defines how to produce outputs from inputs
build: instantiates a rule with specific files
$in / $out: automatic variables for inputs/outputs
phony: a target that is always considered out of date (like .PHONY in make)

7. Ninja sub-tools

bash

# List all build targets
ninja -t targets

# Query dependencies of a target
ninja -t query myapp

# Clean (already mentioned)
ninja -t clean

# Generate compile_commands.json (if supported by generator)
ninja -t compdb cc cxx > compile_commands.json

# List rules
ninja -t rules

8. Common issues

Issue	Cause	Fix
`ninja: error: 'foo.o', needed by 'prog', missing and no known rule to make it`	Missing build rule	Regenerate with CMake; check `add_executable` source list
Build not picking up changes	Stale `build.ninja`	Re-run `cmake -S . -B build`
Very slow parallel build	`-j` too high for I/O-bound build	Use `-l$(nproc)` to limit by load
Circular dependency	Rule depends on itself	Check CMake target dependencies

For the full Ninja command reference, build.ninja format details, and CMake integration patterns, see references/cheatsheet.md.

Use skills/build-systems/cmake for CMake configuration that generates Ninja files
Use skills/build-systems/make for Make-based projects

Files

SKILL.md and 1 other file (references) in skills/build-systems/ninja of mohitmishra786/low-level-dev-skills.

SKILL.md
references/cheatsheet.md

Open the folder on GitHubat commit bdc5847

Compare with similar skills

Ninja next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Ninja compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Ninja this skillmohitmishra786/low-level-dev-skills	253	—	~1.2k	Automated safety check: Pass	MIT	3 mo ago
Qt C++ Code Reviewx-tools-author/x-tools	1.1k	2 repos	~4.3k	Automated safety check: Pass	BSD-3-Clause	6 days ago
YugabyteDB ASH Instrumentationyugabyte/yugabyte-db	11k	—	~4.5k	Automated safety check: Pass	Custom licence	today
pybind11 Release Preparationpybind/pybind11	18k	—	~1.7k	Automated safety check: Pass	Custom licence	today
Qt Cpp ReviewSerial-Studio/Serial-Studio	7.2k	—	~4.3k	Automated safety check: Pass	Custom licence	2 days ago
Paddle Eager GraphPaddlePaddle/Paddle	24k	—	~562	Automated safety check: Pass	Apache-2.0	today

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Questions about Ninja

What does Ninja do?

Ninja build system skill. An agent skill from mohitmishra786/low-level-dev-skills. Ninja is an agent skill from mohitmishra786/low-level-dev-skills. Ninja build system skill.

When should I use Ninja?

Ninja fits situations like: diagnosing Ninja build failures; understanding Ninjas role as a low-level build executor generated by CMake; other meta-build systems; tuning parallelism.

How do I install Ninja in Claude Code?

Run `npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a claude-code`. Or copy the skill folder (skills/build-systems/ninja in mohitmishra786/low-level-dev-skills) into .claude/skills/ninja in your project. Claude Code loads it when a task matches its description.

How do I install Ninja in Codex?

Run `npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a codex`. Or copy the skill folder (skills/build-systems/ninja in mohitmishra786/low-level-dev-skills) into .agents/skills/ninja in your project. Codex loads it when a task matches its description.

Can I use Ninja in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add mohitmishra786/low-level-dev-skills --skill ninja -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/ninja, .gemini/skills/ninja, .github/skills/ninja and .opencode/skills/ninja in your project.

What does Ninja need to run?

Going by SKILL.md and its folder, Ninja needs the command-line tools its instructions call (cmake).

Does Ninja access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Ninja safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Ninja use?

Ninja is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Ninja use?

About 1.2k tokens (SKILL.md is roughly 4.6k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.5k tokens, read only when the agent opens those files.

What are the alternatives to Ninja?

Skills that share tags, products or a category with Ninja: Qt C++ Code Review (x-tools-author/x-tools, 1.1k stars), YugabyteDB ASH Instrumentation (yugabyte/yugabyte-db, 11k stars), pybind11 Release Preparation (pybind/pybind11, 18k stars) and Qt Cpp Review (Serial-Studio/Serial-Studio, 7.2k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Ninja?

mohitmishra786 (a GitHub user) maintains it in mohitmishra786/low-level-dev-skills, which has 253 GitHub stars. The repository holds 138 skills in this directory. The repository was last updated on June 27, 2026.

Source: mohitmishra786/low-level-dev-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Ninja

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Ninja

Purpose

Triggers

Workflow

1. Ninja as a CMake generator

2. Verbose output and diagnostics

3. Common Ninja flags

4. Cleaning

5. compile_commands.json

6. build.ninja format (reference)

7. Ninja sub-tools

8. Common issues

Related skills

Files

Compare with similar skills

Similar skills

More from mohitmishra786/low-level-dev-skills

Related

Questions about Ninja