man bash and search for
command substitution.
Quote:
Command Substitution
Command substitution allows the output of a command to be substituted in place of the command name itself. Command substitution occurs when the command is enclosed as follows:
$(command)
or (“backquoted” version):
`command`
.
.
.
It's been around in
sh already, so it MUST be there. What shell and version do you use?
