Linux CLI Tricks

Re-use last command's arguments	`<new command> !$`
execute last command	`!!`
bind F1 to manual for last command	`bind '"\eOP":"man !!:0\n"'`
test connection to port	`nc --zero --verbose <host> <port>`¹

^[1] you can use telnet, but this doesn't automatically close the connection

see also