pltcl_loadmod: 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/pltcl_loadmod - from package: postgresql-pltcl

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

On Debian possible default full paths are:

/usr/lib/postgresql/9.4/bin/pltcl_loadmod - from package: postgresql-pltcl-9.4

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

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