exact-tandems: 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/exact-tandems - from package: mummer

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

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