Bash Script: Running part of the script in restricted mode

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 built-in.
 * 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 . built-in command.
 * Specifying a filename containing a slash as an argument to the -p option to the hash built-in 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 built-in to replace the shell with another command.
 * Adding or deleting built-in commands with the -f and -d options to the enable built-in.
 * Using the enable built-in command to enable disabled shell built-ins.
 * Specifying the -p option to the command built-in.

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