Errno

Native Rust implementation built into the interpreter. Runtime: PP. See original documentation for the full Perl reference.

Provides system errno constants for Linux. In real Perl, Errno.pm is auto-generated from system headers. We provide the same constants via native Rust implementation using the libc crate.

The module exports constant subs like ENOENT(), EACCES(), etc. that return the errno integer value. It also provides TIEHASH, FETCH, STORE, EXISTS, FIRSTKEY, NEXTKEY methods for the %! tied hash.

Functions

EPERM, ENOENT, ESRCH, … (errno constants)

Each errno name is a constant sub returning its integer value. Over 100 Linux errno constants are provided (see ERRNO_CONSTANTS).

use Errno qw(ENOENT EACCES);
if ($! == ENOENT) { ... }

EXISTS

Checks whether a given name is a known errno constant.

if (exists $!{ENOENT}) { ... }

FETCH

Looks up an errno constant by name through the tied %! hash.

my $val = $!{ENOENT};  # returns 2

FIRSTKEY

Returns the first errno constant name. Used by each %! and keys %!.

my $first = (keys %!)[0];  # "EPERM"

NEXTKEY

Returns the next errno constant name after a given key. Drives hash iteration over %!.

while (my ($k, $v) = each %!) { ... }

TIEHASH

Ties the %! hash to the Errno module. Called implicitly by the runtime.

tie %!, 'Errno';