newgidmap: 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/newgidmap - from package: uidmap

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

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