Errno

📦 min

Symbolic names for the errno(3) values your system uses — EINTR, EAGAIN, ENOENT, EACCES, EEXIST, EIO, ENOTDIR, EISDIR, EBUSY, EPIPE, ECONNRESET, ECONNREFUSED, ETIMEDOUT, and every other errno name the host libc defines.

Most scripts reach for Errno to compare $! against a specific error after a failed system call, or to probe %! for the same purpose without touching $! by name.

Synopsis

use Errno qw(EINTR EAGAIN);

if ($! == EINTR) { retry() }     # function form
if ($!{EAGAIN})  { backoff() }   # hash form via %!

The numeric values come from the libc the pperl binary was built against (Linux glibc or musl), so scripts see exactly the errnos the kernel will actually raise on this host. The :POSIX tag groups the 74 POSIX-standard names for bulk import.

Functions

Predicate helpers

tiehash

Install the tie behind %! so lookups like $!{EINTR} start working.

fetch

Read $!{NAME}: gives the errno value when the last system error matches that name, 0 when the name is a known errno but does not match, and the empty string when the name is not an errno at all.

exists

Answer exists $!{NAME}: true when the name is a known errno on this host, false otherwise. The current value of $! is not consulted.

firstkey

Start iteration over %! — the first key that keys %! or each %! returns.

nextkey

Continue iteration over %! — the errno name that follows the previous one in keys %! or each %!, or undef at the end.

store

Refuse any attempt to write, clear, or delete entries in %!. Assigning to $!{ENOENT}, clearing %!, or deleting a key all raise ERRNO hash is read only!.

tie_it

Internal startup hook that activates the %! tie. Not part of the user-facing API; scripts use %! directly and never call this.