6.10 The Restricted Shell=========================If Bash is started with the name `rbash', or the `--restricted' or `-r'option is supplied at invocation, the shell becomes restricted.  Arestricted shell is used to set up an environment more controlled thanthe standard shell.  A restricted shell behaves identically to `bash'with the exception that the following are disallowed or not performed:   * Changing directories with the `cd' builtin.   * Setting or unsetting the values of the `SHELL', `PATH', `ENV', or     `BASH_ENV' variables.   * Specifying command names containing slashes.   * Specifying a filename containing a slash as an argument to the `.'     builtin command.   * Specifying a filename containing a slash as an argument to the `-p'     option to the `hash' builtin command.   * Importing function definitions from the shell environment at     startup.   * Parsing the value of `SHELLOPTS' from the shell environment at     startup.   * Redirecting output using the `>', `>|', `<>', `>&', `&>', and `>>'     redirection operators.   * Using the `exec' builtin to replace the shell with another command.   * Adding or deleting builtin commands with the `-f' and `-d' options     to the `enable' builtin.   * Using the `enable' builtin command to enable disabled shell     builtins.   * Specifying the `-p' option to the `command' builtin.   * Turning off restricted mode with `set +r' or `set +o restricted'.These restrictions are enforced after any startup files are read.When a command that is found to be a shell script is executed (*noteShell Scripts::), `rbash' turns off any restrictions in the shellspawned to execute the script.