dirsplit: 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/dirsplit - from package: dirsplit

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

On Debian possible default full paths are:

/usr/bin/dirsplit - from package: genisoimage

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

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