genindex.pl: 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/share/texlive/texmf-dist/source/latex/koma-script/doc/bin/genindex.pl - from package: texlive-latex-recommended

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

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