ClaimFile takes a directory and a pattern string containing exactly one asterisk (e.g.

DontSearch determines whether the path to an external command should be taken literally and not searched.

EachExternal calls f for each executable file found while scanning the directories of $E:PATH.

GetHome finds the home directory of a specified user.

Getwd returns path of the working directory in a format suitable as the prompt.

IsExecutable returns whether the FileInfo refers to an executable file.

TildeAbbr abbreviates the user's home directory to ~.

ErrClaimFileBadPattern is thrown when the pattern argument passed to ClaimFile does not contain exactly one asterisk.