znew: 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/znew - from package: gzip

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

On Debian possible default full paths are:

/bin/znew - from package: gzip

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

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