impala: 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/impala - from package: blast2

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

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