zshdb: 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 Debian possible default full paths are:

/usr/bin/zshdb - from package: zshdb

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

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