Perl Programming/Keywords/-t
The -t keyword
[edit | edit source]-t is a file test that tests if the filehandle is opened to a TTY.
It takes one argument, either a FILENAME, a FILEHANDLE, or a DIRHANDLE to test the associated file to see, if something is true about it. If the argument is omitted, it tests STDIN. -t returns 1 for true and an empty string for false. If the file doesn't exist or can't be examined, it returns undef and sets $! (errno).
Syntax
[edit | edit source] -t FILENAME -t FILEHANDLE -t EXPRESSION -t DIRHANDLE -t