gant: 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/gant - from package: gant
/usr/share/groovy/bin/gant - from package: gant

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

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