pg_archivecleanup: 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 Debian possible default full paths are:

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

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

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