zserv: 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/zserv - from package: cernlib-packlib

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

On Debian possible default full paths are:

/usr/sbin/zserv - from package: pawserv

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

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