All of the following options except for ‘disabled-builtins’, ‘directpand-default’, and ‘xpg-echo-default’ are enabled by default, unless the operating system does not provide the necessary support.
--enable-alias
Allow alias expansion and include the alias and unalias builtins (see
Section 6.6 [Aliases], page 88).
--enable-arith-for-command
Include support for the alternate form of the for command that behaves like the
C language for statement (see Section 3.2.4.1 [Looping Constructs], page 10).
--enable-array-variables
Include support for one-dimensional array shell variables (see Section 6.7 [Ar- rays], page 89).
--enable-bang-history
Include support for csh-like history substitution (see Section 9.3 [History In- teraction], page 135).
--enable-brace-expansion
Include csh-like brace expansion ( b{a,b}c 7→ bac bbc ). See Section 3.5.1
[Brace Expansion], page 21, for a complete description.
--enable-casemod-attributes
Include support for case-modifying attributes in the declare builtin and as- signment statements. Variables with the uppercase attribute, for example, will have their values converted to uppercase upon assignment.
--enable-casemod-expansion
Include support for case-modifying word expansions.
--enable-command-timing
Include support for recognizing time as a reserved word and for displaying timing statistics for the pipeline following time (see Section 3.2.2 [Pipelines], page 8). This allows pipelines as well as shell builtins and functions to be timed.
--enable-cond-command
Include support for the [[ conditional command. (see Section 3.2.4.2 [Condi- tional Constructs], page 10).
--enable-cond-regexp
Include support for matching posix regular expressions using the ‘=~’ binary operator in the [[ conditional command. (see Section 3.2.4.2 [Conditional Con- structs], page 10).
--enable-coprocesses
Include support for coprocesses and the coproc reserved word (see Section 3.2.2
[Pipelines], page 8).
--enable-debugger
Include support for the bash debugger (distributed separately).