cksfv: 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/bin/cksfv - from package: cksfv

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

On Debian possible default full paths are:

/usr/bin/cksfv - from package: cksfv

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

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