koi8rxterm: 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 CentOS possible default full paths are:

/usr/bin/koi8rxterm - from package: xterm

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/koi8rxterm - from package: xterm

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

Error in other languages:
koi8rxterm: bevel nie gevind nie
koi8rxterm: comandă negăsită
koi8rxterm: comando não encontrado
koi8rxterm: commande introuvable
koi8rxterm: command not found
koi8rxterm: käsku ei ole
koi8rxterm: không tìm thấy lệnh
koi8rxterm: komanda nerasta
koi8rxterm: Kommando nicht gefunden.
koi8rxterm: kommandot finns inte
koi8rxterm: komut yok
koi8rxterm: nie znaleziono polecenia
koi8rxterm: níor aimsíodh an t-ordú
koi8rxterm: no se encontró la orden
koi8rxterm: no s'ha trobat l'ordre
koi8rxterm: opdracht niet gevonden
koi8rxterm: parancs nem található
koi8rxterm: perintah tidak ditemukan
koi8rxterm: príkaz nenájdený
koi8rxterm: příkaz nenalezen
koi8rxterm: команда не найдена
koi8rxterm: командата не е открита
koi8rxterm: 命令找不到
koi8rxterm: コマンドが見つかりません