16.10 The Restricted Shell
2=========================
3
4If Bash is started with the name `rbash', or the `--restricted' or `-r'
5option is supplied at invocation, the shell becomes restricted.  A
6restricted shell is used to set up an environment more controlled than
7the standard shell.  A restricted shell behaves identically to `bash'
8with the exception that the following are disallowed or not performed:
9
10   * Changing directories with the `cd' builtin.
11
12   * Setting or unsetting the values of the `SHELL', `PATH', `ENV', or
13     `BASH_ENV' variables.
14
15   * Specifying command names containing slashes.
16
17   * Specifying a filename containing a slash as an argument to the `.'
18     builtin command.
19
20   * Specifying a filename containing a slash as an argument to the `-p'
21     option to the `hash' builtin command.
22
23   * Importing function definitions from the shell environment at
24     startup.
25
26   * Parsing the value of `SHELLOPTS' from the shell environment at
27     startup.
28
29   * Redirecting output using the `>', `>|', `<>', `>&', `&>', and `>>'
30     redirection operators.
31
32   * Using the `exec' builtin to replace the shell with another command.
33
34   * Adding or deleting builtin commands with the `-f' and `-d' options
35     to the `enable' builtin.
36
37   * Using the `enable' builtin command to enable disabled shell
38     builtins.
39
40   * Specifying the `-p' option to the `command' builtin.
41
42   * Turning off restricted mode with `set +r' or `set +o restricted'.
43
44These restrictions are enforced after any startup files are read.
45
46When a command that is found to be a shell script is executed (*note
47Shell Scripts::), `rbash' turns off any restrictions in the shell
48spawned to execute the script.
49
50