select - display a menu
select name [ in word ... term ] do list done
This command is a Korn-shell built-in command.
The select(1) command provides an automatic method of presenting the user with a menu and selecting from it.
The term argument is either a newline or a semicolon (;). An enumerated list of the specified words is printed on standard error, followed by a prompt (PS3, normally '#? '). A number corresponding to one of the enumerated words is then read from standard input, name is set to the selected word (or is unset if the selection is not valid), REPLY is set to what was read (leading/trailing space is stripped), and list is executed. If a blank line (that is, zero or more IFS characters) is entered, the menu is reprinted without executing list.
When list completes, the enumerated list is printed if REPLY is null, the prompt is printed, and so on. This process is repeated until an end-of-file is read, an interrupt is received, or a break statement is executed inside the loop.
If in word ... is omitted, the positional parameters are used (such as "$1", "$2").
For historical reasons, open and close braces can be used instead of do and done (for example, select i; { echo $i; }).
The exit status of a select statement is zero if a break statement is used to exit the loop; otherwise, it is non-zero.