How to tell if my program is being piped to another (Perl) -

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"ls" behaves differently when output being piped: 

  > ls ???  bar  foo  > ls ??? | cat  bar  foo

how know, , how in perl?

in perl, -t file test operator indicates whether filehandle (including stdin) connected terminal.

there -p test operator indicate whether filehandle attached pipe.

$ perl -e 'printf "term:%d, pipe:%d\n", -t stdin, -p stdin' term:1, pipe:0 $ perl -e 'printf "term:%d, pipe:%d\n", -t stdin, -p stdin' < /tmp/foo term:0, pipe:0 $ echo foo | perl -e 'printf "term:%d, pipe:%d\n", -t stdin, -p stdin' term:0, pipe:1

file test operator documentation @ perldoc -f -x.


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