Detecting Pipes in Perl
Published on 30 Nov 2007Tags #Perl
This is something you won’t need each and every day of your life but I won’t have to rethink it once I need it ;-)
test.pl:
#!/usr/bin/perl
if (-c STDIN) { print STDERR 'stdin : char' . "n";
} elsif (-p STDIN) { print STDERR 'stdin : pipe' . "n";
} elsif (-f STDIN) { print STDERR 'stdin : file' . "n";
}
if (-c STDIN) { print STDERR 'stdout: char' . "n";
} elsif (-p STDIN) { print STDERR 'stdout: pipe' . "n";
} elsif (-f STDIN) { print STDERR 'stdout: file' . "n";
}
print STDERR "n";
tests:
$ ./test.pl
stdin : char
stdout: char
$ cat file | ./test.pl
stdin : pipe
stdout: char
$ ./test.pl < file
stdin : file
stdout: char
$ ./test.pl | cat
stdin : char
stdout: pipe
$ ./test.pl > file
stdin : char
stdout: file
$ ./test.pl > /dev/null
stdin : char
stdout: char
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