... example, +10 means " ;10 lines following," but + 10 means " ;11 lines following (1 + 10 )," which is probably not what you mean (or want). The number 0 stands for the top of the file ... versions of the ed editor use % as the sole character in the replacement text to mean " ;the replacement text of the last substitute command." \u or \l 5.3 .1 Renaming the Buffer You ... s/thier/their/ Delete lines 1 through 3 (leaving you now on the top line of the file); then make a substitution on the current line (which was line 4 before you invoked the ex prompt). :1, 5 m 10 ...