yank: 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/yank - from package: emboss

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

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