splain: 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/splain - from package: perl

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

On Debian possible default full paths are:

/usr/bin/splain - from package: perl

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

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