sub is_interactive { # Not interactive if output is not to terminal... return 0 if not -t *STDOUT; # If *ARGV is opened, we're interactive if... if (openhandle *ARGV) { # ...it's currently opened to the magic '-' file return -t *STDIN if $ARGV eq '-'; # ...it's at end-of-file and the next file is the magic '-' file return @ARGV>0 && $ARGV[0] eq '-' && -t *STDIN if eof *ARGV; # ...it's directly attached to the terminal return -t *ARGV; } # If *ARGV isn't opened, it will be interactive if *STDIN is attached # to a terminal and either there are no files specified on the command line # or if there are one or more files and the first is the magic '-' file return -t *STDIN && (@ARGV==0 || $ARGV[0] eq '-'); } # and later... if (is_interactive()) { print $PROMPT; }