sks-recon: 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-recon - from package: sks

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

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