signset-editor: 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/signset-editor - from package: dnssec-tools

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

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