errno: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/errno - from package: moreutils

You may install the required package with command apt-get install {package}
Error in other languages:
errno: bevel nie gevind nie
errno: comandă negăsită
errno: comando não encontrado
errno: commande introuvable
errno: command not found
errno: käsku ei ole
errno: không tìm thấy lệnh
errno: komanda nerasta
errno: Kommando nicht gefunden.
errno: kommandot finns inte
errno: komut yok
errno: nie znaleziono polecenia
errno: níor aimsíodh an t-ordú
errno: no se encontró la orden
errno: no s'ha trobat l'ordre
errno: opdracht niet gevonden
errno: parancs nem található
errno: perintah tidak ditemukan
errno: príkaz nenájdený
errno: příkaz nenalezen
errno: команда не найдена
errno: командата не е открита
errno: 命令找不到
errno: コマンドが見つかりません