corkscrew: command not found

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/corkscrew - from package: corkscrew

You may install the required package with command apt-get install {package}

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