If you want to clear the screen, the “ANSI” sequence in a printf
\033[2J
clears the entire screen, e.g.,
printf '\033[2J'
The command-line clear program uses this, along with moving the cursor to the “home” position, again an “ANSI” sequence:
\033[H
The program gets the information from the terminal database. For example, for TERM=vt100, it might see this (using \E as \033):
clear=\E[H\E[J$<50>
(the $<50> indicates padding needed for real VT100s). You might notice that the 2 is absent from this string. That is because the cursor is first moved to the home (upper left) position, and the 2 (entire screen) is not necessary. Eliminating that from the string made VT100s a little faster.
On the other hand, if you just want to reset the terminal, you can use the VT100-style RIS:
\033c
but that has side-effects, besides not being in ECMA-48. These bug reports were for side-effects of \033c:
- Debian Bug report logs – #60377
“reset” broken for dumb terminals - Debian Bug report logs – #239205
“reset changes a unicode console to non-unicode”
Further reading:
- Why doesn’t the screen clear when I type control/L?
- XTerm Control Sequences
CSI Ps J Erase in Display (ED).
Ps = 0 -> Erase Below (default).
Ps = 1 -> Erase Above.
Ps = 2 -> Erase All.
Ps = 3 -> Erase Saved Lines (xterm).
- ECMA-48: Control Functions for Coded Character Sets