yac2ncid: 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/yac2ncid - from package: ncid

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

Error in other languages:
yac2ncid: bevel nie gevind nie
yac2ncid: comandă negăsită
yac2ncid: comando não encontrado
yac2ncid: commande introuvable
yac2ncid: command not found
yac2ncid: käsku ei ole
yac2ncid: không tìm thấy lệnh
yac2ncid: komanda nerasta
yac2ncid: Kommando nicht gefunden.
yac2ncid: kommandot finns inte
yac2ncid: komut yok
yac2ncid: nie znaleziono polecenia
yac2ncid: níor aimsíodh an t-ordú
yac2ncid: no se encontró la orden
yac2ncid: no s'ha trobat l'ordre
yac2ncid: opdracht niet gevonden
yac2ncid: parancs nem található
yac2ncid: perintah tidak ditemukan
yac2ncid: príkaz nenájdený
yac2ncid: příkaz nenalezen
yac2ncid: команда не найдена
yac2ncid: командата не е открита
yac2ncid: 命令找不到
yac2ncid: コマンドが見つかりません