pbsnodes: 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/pbsnodes - from package: torque-client

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

On Debian possible default full paths are:

/usr/bin/pbsnodes - from package: slurm-wlm-torque

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

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