Install the pre-commit hooks.

def install(
        config_file, store,
        overwrite=False, hooks=False, hook_type='pre-commit',
        skip_on_missing_conf=False,
):
    """Install the pre-commit hooks."""
    if cmd_output('git', 'config', 'core.hooksPath', retcode=None)[1].strip():
        logger.error(
            'Cowardly refusing to install hooks with `core.hooksPath` set.\n'
            'hint: `git config --unset-all core.hooksPath`',
        )
        return 1

    hook_path, legacy_path = _hook_paths(hook_type)

    mkdirp(os.path.dirname(hook_path))

    # If we have an existing hook, move it to pre-commit.legacy
    if os.path.lexists(hook_path) and not is_our_script(hook_path):
        shutil.move(hook_path, legacy_path)

    # If we specify overwrite, we simply delete the legacy file
    if overwrite and os.path.exists(legacy_path):
        os.remove(legacy_path)
    elif os.path.exists(legacy_path):
        output.write_line(
            'Running in migration mode with existing hooks at {}\n'
            'Use -f to use only pre-commit.'.format(legacy_path),
        )

    params = {
        'CONFIG': config_file,
        'HOOK_TYPE': hook_type,
        'INSTALL_PYTHON': sys.executable,
        'SKIP_ON_MISSING_CONFIG': skip_on_missing_conf,
    }

    with io.open(hook_path, 'w') as hook_file:
        contents = resource_text('hook-tmpl')
        before, rest = contents.split(TEMPLATE_START)
        to_template, after = rest.split(TEMPLATE_END)

        before = before.replace('#!/usr/bin/env python3', shebang())

        hook_file.write(before + TEMPLATE_START)
        for line in to_template.splitlines():
            var = line.split()[0]
            hook_file.write('{} = {!r}\n'.format(var, params[var]))
        hook_file.write(TEMPLATE_END + after)
    make_executable(hook_path)

    output.write_line('pre-commit installed at {}'.format(hook_path))

    # If they requested we install all of the hooks, do so.
    if hooks:
        install_hooks(config_file, store)

    return 0