gpaint: 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/gpaint - from package: gpaint

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

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