plser: 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/plser - from package: gnustep-base

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

On Debian possible default full paths are:

/usr/bin/plser - from package: gnustep-base-runtime

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

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