cp can also be dangerous
After several years working in a DOS environment I got a job as project Manager / Sys admin on a Unix based customer site for a six month stint. On my second day I wanted to use a test system to learn the software more, so decided to copy the live order files to the test system.
Unfortunately I forgot the trailing full stop as it was not needed in DOS - so the live order index file over wrote the live data file. And the company only took orders for next day delivery so it wiped all current orders.
Luckily it printed a sales acknowledgement every time an order was placed so I escaped death and learned never miss the second parameter with cp command.