texindex: 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 CentOS possible default full paths are:

/usr/bin/texindex - from package: texinfo-tex

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/texindex - from package: texinfo

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

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