listplugins: 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/listplugins - from package: ladspa

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

On Debian possible default full paths are:

/usr/bin/listplugins - from package: ladspa-sdk

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

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