p7zip: 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/p7zip - from package: p7zip

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

Error in other languages:
p7zip: bevel nie gevind nie
p7zip: comandă negăsită
p7zip: comando não encontrado
p7zip: commande introuvable
p7zip: command not found
p7zip: käsku ei ole
p7zip: không tìm thấy lệnh
p7zip: komanda nerasta
p7zip: Kommando nicht gefunden.
p7zip: kommandot finns inte
p7zip: komut yok
p7zip: nie znaleziono polecenia
p7zip: níor aimsíodh an t-ordú
p7zip: no se encontró la orden
p7zip: no s'ha trobat l'ordre
p7zip: opdracht niet gevonden
p7zip: parancs nem található
p7zip: perintah tidak ditemukan
p7zip: príkaz nenájdený
p7zip: příkaz nenalezen
p7zip: команда не найдена
p7zip: командата не е открита
p7zip: 命令找不到
p7zip: コマンドが見つかりません