zfs-show: a wrapper to `zfs get` to show values from multiple properties in a table nicely

zfs-show

#!/usr/bin/env python3

import sys
import subprocess
from collections import namedtuple, OrderedDict

Record = namedtuple('Record', 'name property value source')

def get_widths(item):
  return [len(x) for x in item.values()]

def main(argv):
  output = subprocess.check_output(['zfs', 'get'] + argv)
  items = []
  lines_iter = iter(output.decode().splitlines())
  next(lines_iter)
  for l in lines_iter:
    rec = Record(*l.split())
    if items and items[-1]['name'] == rec.name:
      items[-1][rec.property] = rec.value
    else:
      d = OrderedDict()
      d['name'] = rec.name
      d[rec.property] = rec.value
      items.append(d)

  if not items:
    return

  widths = [get_widths(x) for x in items]
  # header
  widths.append([len(x) for x in items[0].keys()])
  column_widths = [max(x) for x in zip(*widths)]
  fmt = '%%-%ds' % column_widths[0]
  fmt += '  '.join('%%%ds' % w for w in column_widths[1:])

  print(fmt % tuple(items[0].keys()))
  for x in items:
    print(fmt % tuple(x.values()))

if __name__ == '__main__':
  main(sys.argv[1:])