par-archive: 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/par-archive - from package: libpar-packer-perl

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

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