unixterm: 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/unixterm - from package: vde2

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

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