vala-terminal: 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/vala-terminal - from package: vala-terminal

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

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