prlimit: 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/prlimit - from package: util-linux

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

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