If Bash is started with the name
rbash, or the
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
with the exception that the following are disallowed or not performed:
SHELLOPTSfrom the shell environment at startup.
execbuiltin to replace the shell with another command.
enablebuiltin command to enable disabled shell builtins.
These restrictions are enforced after any startup files are read.
When a command that is found to be a shell script is executed
(see Shell Scripts),
rbash turns off any restrictions in
the shell spawned to execute the script.