BackupPC: 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/share/BackupPC/bin/BackupPC - from package: BackupPC

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

On Debian possible default full paths are:

/usr/share/BackupPC/bin/BackupPC - from package: BackupPC

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

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