u
create a UNIX subshell
SYNOPSIS
u [shell_command]
DESCRIPTION
The u macro is a general escape to a UNIX shell. If invoked with arguments, the arguments are executed as a command by the Bourne shell, /bin/sh.
Without an argument, an interactive subshell is spawned. The program used for the subshell is taken from the environment variable SHELL, if set. Otherwise, the Bourne shell is used. Exit the subshell to return to spec. Don't launch spec again from the subshell.
DEFINITION
def u 'unix("$*")'
EXAMPLE
u contents 900110