pcp_promote_node: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/pcp_promote_node - from package: postgresql-pgpool-II

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

On Debian possible default full paths are:

/usr/sbin/pcp_promote_node - from package: pgpool2

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