complex: 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/complex - from package: ladr4-apps

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

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