plasmapkg: 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/plasmapkg - from package: kdebase-runtime

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

On Debian possible default full paths are:

/usr/bin/plasmapkg - from package: kde-runtime

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

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