vacuumlo: 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/vacuumlo - from package: postgresql-contrib

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

On Debian possible default full paths are:

/usr/bin/vacuumlo - from package: postgresql-client-common
/usr/lib/postgresql/9.4/bin/vacuumlo - from package: postgresql-contrib-9.4

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

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