blkid: 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/blkid - from package: util-linux-ng

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

On Debian possible default full paths are:

/sbin/blkid - from package: util-linux

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

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