trustman: 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/trustman - from package: dnssec-tools

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

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