The first time I truly utilized cat -v was when I needed to know a certain keys in a terminal emulator, for example Shift+Left:


$ cat -v
^[[1;2D

-v will show those non-printing characters, using ^ for control and M- for alt as notations, except for LFD (Line Feed) and TAB (Tab Key). In that special exception, hexdump or od can help, or you can use -T (--show-tabs) for tabs:


$ echo -ne '\t\n' | cat -v

$ echo -ne '\t\n' | cat -vT
^I

$ echo -ne '\t\n' | hexdump
0000000 0a09
0000002

$ echo -ne '\t\n' | od -c

0000000 \t  \n
0000002

I found it’s not only helpful for troubleshooting key control characters, but also for finding out what exactly does tput output to terminal, for example:


$ tput clear | cat -v
^[[H^[[J

$ tput reset | cat -v
^[c^[[?1000l^[[?25h