termidx: 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/termidx - from package: joe

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

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