e2label: 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:

/sbin/e2label - from package: e2fsprogs

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

On Debian possible default full paths are:

/sbin/e2label - from package: e2fsprogs

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

Error in other languages:
e2label: bevel nie gevind nie
e2label: comandă negăsită
e2label: comando não encontrado
e2label: commande introuvable
e2label: command not found
e2label: käsku ei ole
e2label: không tìm thấy lệnh
e2label: komanda nerasta
e2label: Kommando nicht gefunden.
e2label: kommandot finns inte
e2label: komut yok
e2label: nie znaleziono polecenia
e2label: níor aimsíodh an t-ordú
e2label: no se encontró la orden
e2label: no s'ha trobat l'ordre
e2label: opdracht niet gevonden
e2label: parancs nem található
e2label: perintah tidak ditemukan
e2label: príkaz nenájdený
e2label: příkaz nenalezen
e2label: команда не найдена
e2label: командата не е открита
e2label: 命令找不到
e2label: コマンドが見つかりません