open

Open a file by path, returning a raw file descriptor.

Synopsis

use POSIX qw(open O_RDONLY O_CREAT O_WRONLY);
my $fd = open($path, O_RDONLY)
    or die "open: $!";

What you get back

A non-negative integer fd on success, undef on failure (with $! set). This is the raw system fd, not a Perl filehandle — pair it with POSIX::close or convert via IO::Handle::fdopen.

Differences from upstream

Fully compatible with upstream POSIX. Third argument $mode defaults to 0666 when opening with O_CREAT and no mode given.

See also

• close, dup, lseek, read, write — the rest of the raw fd API.

• Core open — the Perl-native filehandle interface.