psnup: 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/psnup - from package: psutils

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

On Debian possible default full paths are:

/usr/bin/psnup - from package: psutils

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

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