Erase Character (ECH)

The parameter n must be an integer greater than or equal to 1. If n is less than or equal to 0, adjust n to be 1. If n is omitted, n defaults to 1.

The rightmost column that can be erased is the rightmost column of the screen. The right margin has no effect on this sequence.

This sequence always unsets the pending wrap state. If the row under the cursor is soft-wrapped, then the soft-wrap state is also reset.

For n cells up to the rightmost column, blank the cell by replacing it with an empty character with the background color colored according to the current SGR state. No other SGR attributes are preserved.

If a multi-cell character would be split, erase the full multi-cell character. For example, if “橋” is printed and ECH n = 1 is issued, the full character should be erased even though it takes up two cells. Both erased cells are colored with the current background color according to the current SGR state.

If Select Character Selection Attribute (DECSCA) is enabled or was the most recently enabled protection mode on the currently active screen, protected attributes are ignored as if they were never set and the cells with them are erased. It does not matter if DECSCA is currently disabled, protected attributes are still ignored so long as DECSCA was the most recently enabled protection mode.

If DECSCA is not currently enabled and was not the most recently enabled protection mode on the currently active screen, cells with the protected attribute set are respected and not erased but still count towards n. It does not matter if the protection attribute for a cell was originally set from DECSCA.

Validation

ECH V-1: Simple Operation

printf "ABC"
printf "\033[1G"
printf "\033[2X"

|c_C_____|

ECH V-2: Erasing Beyond Edge of Screen

cols=$(tput cols)
printf "\033[${cols}G"
printf "\033[2D"
printf "ABC"
printf "\033[D"
printf "\033[10X"

|_____Ac_|

ECH V-3: Reset Pending Wrap State

cols=$(tput cols)
printf "\033[${cols}G" # move to last column
printf "A" # set pending wrap state
printf "\033[X"
printf "X"

|_______Xc

ECH V-4: SGR State

printf "ABC"
printf "\033[1G"
printf "\033[41m"
printf "\033[2X"

|c_C_____|

The c_ cells should both have a red background. All other cells remain unchanged in style.

ECH V-5: Multi-cell Character

printf "橋BC"
printf "\033[1G"
printf "\033[X"
printf "X"

|XcBC____|

ECH V-6: Left/Right Scroll Region Ignored

printf "\033[1;1H" # move to top-left
printf "\033[0J" # clear screen
printf "\033[?69h" # enable left/right margins
printf "\033[1;3s" # scroll region left/right
printf "\033[4G"
printf "ABC"
printf "\033[1G"
printf "\033[4X"

|c___BC____|

ECH V-7: Protected Attributes Ignored with DECSCA

printf "\033V"
printf "ABC"
printf "\033[1\"q"
printf "\033[0\"q"
printf "\033[1G"
printf "\033[2X"

|c_C_______|

ECH V-8: Protected Attributes Respected without DECSCA

printf "\033[1\"q"
printf "ABC"
printf "\033V"
printf "\033[1G"
printf "\033[2X"

|ABC_______|

The cursor remains at A.