sks-db: 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/sbin/sks-db - from package: sks

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

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