7z: 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/7z - from package: p7zip-plugins

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

On Debian possible default full paths are:

/usr/bin/7z - from package: p7zip-full

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

Error in other languages:
7z: bevel nie gevind nie
7z: comandă negăsită
7z: comando não encontrado
7z: commande introuvable
7z: command not found
7z: käsku ei ole
7z: không tìm thấy lệnh
7z: komanda nerasta
7z: Kommando nicht gefunden.
7z: kommandot finns inte
7z: komut yok
7z: nie znaleziono polecenia
7z: níor aimsíodh an t-ordú
7z: no se encontró la orden
7z: no s'ha trobat l'ordre
7z: opdracht niet gevonden
7z: parancs nem található
7z: perintah tidak ditemukan
7z: príkaz nenájdený
7z: příkaz nenalezen
7z: команда не найдена
7z: командата не е открита
7z: 命令找不到
7z: コマンドが見つかりません