seahorse-tool: 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/seahorse-tool - from package: seahorse-plugins

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

On Debian possible default full paths are:

/usr/bin/seahorse-tool - from package: seahorse-nautilus

You may install the required package with command apt-get install {package}

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