diatheke: 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 CentOS possible default full paths are:

/usr/bin/diatheke - from package: sword

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/diatheke - from package: diatheke

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

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