blkcat: 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 Debian possible default full paths are:

/usr/bin/blkcat - from package: sleuthkit

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

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