ast_link: 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/ast_link - from package: ast-devel

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

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