krita: command not found

Have You tried accessing the binary with the full path?

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/krita - from package: krita

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