The ubuntu system cleans up caches, logs and useless packages to reduce memory usage

Clean up junk logs

Junk log files are generally in /var/log/journal/, and can be cleared by the following command

#检查日志大小
journalctl --disk-usage 

#只保留一周（时间可选）的日志
sudo journalctl --vacuum-time=1w 

#只保留500MB（可选）的日志
sudo journalctl --vacuum-size=500M    

Clear cache and unused packages

#删除旧版本软件缓存
sudo apt-get autoclean       

#删除系统内所有软件缓存
sudo apt-get clean               

#删除系统不再使用的孤立软件
sudo apt-get autoremove