seinfo: 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/seinfo - from package: setools-console

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

On Debian possible default full paths are:

/usr/bin/seinfo - from package: setools

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

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