inter: 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/lib/x86_64-linux-gnu/gap/pkg/guava/bin/leon/inter - from package: gap-guava-bin

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

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