If the in word is omitted, use the positional parameters. If this line consists of the number of one of the listed word s, then the parameter name is set to the word corresponding to this number. If this line is empty, the selection list is printed again. Otherwise, the value of the parameter name is set to null. Execute list in a subshell.
Traps set by the trap builtin are reset to their default values while executing list .
Define a function which is referenced by any one of word . See section Functions . If pipeline is omitted, print statistics about the shell process and its children. Evaluates the conditional expression exp and return a zero exit status if it is true. See section Conditional Expressions , for a description of exp .