cmd_wd: define the working directory.
cmd_envvar: define the environment variables.
cmd_envpath: define the PATH-like environment variables.
cmd_wd(command, wd = NULL)cmd_envvar(command, ..., action = "replace", sep = " ")
cmd_envpath(command, ..., action = "prefix", name = "PATH")
cmd_wd: The command object itself, with working directory updated.
cmd_envvar: The command object itself, with running environment
variable updated.
cmd_envpath: The command object self, with running environment variable
name updated.
A command object.
A string or NULL define the working directory of the command.
cmd_envvar: Named character define the environment variables.
cmd_envpath: Unnamed character to define the PATH-like environment
variables name.
Should the new values "replace", "prefix" or "suffix"
existing environment variables?
A string to separate new and old value when action is "prefix"
or "suffix".
A string define the PATH environment variable name. You
can use this to define other PATH-like environment variable such as
PYTHONPATH.
cmd_run()/cmd_background()/cmd_help()