omp-cli: 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/omp-cli - from package: openvas-client

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

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