Delete the first known character in a string with sed

Question

How does one delete the first known character in a string with sed?

For example, say I want to delete the first character (which is @) in the string "@ABCDEFG1234"

I want sed to verify whether "@" exists as the first character. If so, it should delete the character.

Answer 1

sed 's/^@\(.*\)/\1/'

^ means beginning of the string

@ your known char

(.*) the rest, captured

then captured block will be substituted to output Sorry, can't test it at the moment, but should be something like that

Answer 2

There's no need to capture and replace.

sed 's/^@//'

This replaces the character @ when it's first ^ in the string, with nothing. Thus, deleting it.