lddtree.sh: 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/lddtree.sh - from package: pax-utils

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

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