mydnsimport-pgsql: 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/mydnsimport-pgsql - from package: mydns-pgsql

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

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