gchempaint: 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/gchempaint - from package: gchempaint

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

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