The : command is often used in shell script
s to trap
and ignore signals
received by the script.
trap : 1 2 3 9 15
will cause the shell
ignore any signal 1, 2, 3, or 15 sent to it while executing commands in the script.
Sorry, Nobody can ignore a signal 9
Re: ":" and vi
. Technically, ":" is an escape
from the visual front-end
out to the underlying editing program, ex
. Typing a : inside vi allows you to execute any ex
command. This escape key is a colon because ex
's traditional prompt is a colon.