start-dirsrv: 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/sbin/start-dirsrv - from package: 389-ds-base

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

On Debian possible default full paths are:

/usr/sbin/start-dirsrv - from package: 389-ds-base

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

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