monoのバージョンを簡単に変えたかった．macでbrewとかじゃなくてインストーラーで入れてる場合はこれで対応できるはず

mono_switch.py

#!/usr/bin/env python3
import itertools
import sys
import subprocess

process = subprocess.run('ls /Library/Frameworks/Mono.framework/Versions/',
	shell=True,
	stdout=subprocess.PIPE)

versions = [v for v in  process.stdout.decode('utf-8').strip().split() if v != 'Current']
column_max = 9 if len(versions) > 9 else len(versions)

versions_list = [[f for f in feats] for feats in itertools.zip_longest(*[iter(versions)]*column_max)]

page_index = 0

def print_select_field(colums, column_max = 9, has_next = False, is_initialize = False):
    if not is_initialize:
        for _ in range(column_max + 2):
            print('\033[2A', file=sys.stderr)
            print('\033[2K', file=sys.stderr)
            print('\033[2A', file=sys.stderr)
        pass

    for i, col in enumerate(colums, 1):
        if col is not None:
            print(f'{i}. {col}')
        else:
            print('')
    
    if has_next: print('0. next')


print('Select with number key')
process = subprocess.run('ls -l /Library/Frameworks/Mono.framework/Versions/Current', shell=True, stdout=subprocess.PIPE)
print(f'Current is {process.stdout.decode("utf-8").strip().split()[-1]}')
print_select_field(versions_list[page_index], column_max, len(versions_list) != 1, True)

while True:
    n = int(input())
    if n == 0:
        page_index = (page_index + 1) % len(versions_list)
        print_select_field(versions_list[page_index], column_max, len(versions_list) != 1)
    elif 0 < n and n < column_max + 1:
    	selected_version = versions_list[page_index][n - 1]
    	proc = subprocess.run(f'sudo ln -snf /Library/Frameworks/Mono.framework/Versions/{selected_version} /Library/Frameworks/Mono.framework/Versions/Current', shell=True)
    	break