ulqda: 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/ulqda - from package: texlive-science

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

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