chk_tree: 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/chk_tree - from package: torque-client

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

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