System stats without psutil on macOS

Getting CPU usage, memory statistics, and disk space information on macOS for a monitoring dashboard, system tray app, or CLI tool. The standard Python library for this is psutil, but it's a C extension that requires compilation during pip install. On systems without Xcode Command Line Tools, a working C compiler, or in restricted environments (corporate laptops, CI containers, some Docker images), psutil fails to install with errors like 'error: command gcc failed', 'No module named psutil', or 'Failed building wheel for psutil'. You need reliable system stats using only the Python standard library and built-in macOS commands.

Use these stdlib-only approaches for each metric:

1. CPU USAGE (parse top output):

import subprocess
def get_cpu_percent():
output = subprocess.check_output(
['top', '-l', '1', '-n', '0', '-stats', 'cpu'],
text=True, timeout=5
)
for line in output.split('\n'):
if 'CPU usage' in line:
parts = line.split()
user = float(parts[2].replace('%', ''))
sys_ = float(parts[4].replace('%', ''))
return round(user + sys_, 1)
return 0.0

1. MEMORY (vm_stat + sysctl):

import subprocess
def get_memory():
total = int(subprocess.check_output(
['sysctl', '-n', 'hw.memsize'], text=True
).strip())
vm = subprocess.check_output(['vm_stat'], text=True)
pages = {}
for line in vm.split('\n'):
if ':' in line:
key, val = line.split(':')
pages[key.strip()] = int(val.strip().rstrip('.') or 0)
page_size = 4096
used = (pages.get('Pages active', 0) + pages.get('Pages wired down', 0)) * page_size
return {'total_gb': round(total / 1e9, 1), 'used_gb': round(used / 1e9, 1), 'percent': round(used / total * 100, 1)}

1. DISK SPACE (os.statvfs — pure stdlib):

import os
def get_disk(path='/'):
st = os.statvfs(path)
total = st.f_blocks * st.f_frsize
free = st.f_bavail * st.f_frsize
used = total - free
return {'total_gb': round(total / 1e9, 1), 'free_gb': round(free / 1e9, 1), 'percent': round(used / total * 100, 1)}

1. GRACEFUL PSUTIL FALLBACK pattern:

try:
import psutil
cpu = psutil.cpu_percent(interval=1)
except ImportError:
cpu = get_cpu_percent()

psutil is a C extension that wraps platform-specific system calls. It requires compilation during installation, which needs a C compiler (gcc/clang) and Python development headers. On macOS this means Xcode Command Line Tools must be installed — a 1.2GB download that many users don't have. The fallback approach uses only subprocess (stdlib) and os.statvfs (stdlib). These commands are guaranteed to exist on every macOS installation.

Building monitoring tools on macOS without C compiler