coala: 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/coala - from package: coala

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

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