| 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. A |
| restricted shell is used to set up an environment more controlled than |
| the 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 (*note |
| Shell Scripts::), `rbash' turns off any restrictions in the shell |
| spawned to execute the script. |
| |