This procedure looks up the error message string corresponding to an error number and returns the result as a string.
The error message as returned by the C-library function strerror() is returned as a string.
> (strerror (errno)) "Undefined error: 0" > (define p (open-input-file "unknown")) ERROR! message : cannot open file irritant : #<primitive-procedure internal-open-input-file> expression: fname continue : possible, continue with value as value from primitive Error (? for help) >> > (strerror (errno)) "No such file or directory" > (strerror 22) "Invalid argument" >