doveconf: 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/doveconf - from package: dovecot

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

On Debian possible default full paths are:

/usr/bin/doveconf - from package: dovecot-core

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

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