i3blocks: 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/i3blocks - from package: i3blocks

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

Error in other languages:
i3blocks: bevel nie gevind nie
i3blocks: comandă negăsită
i3blocks: comando não encontrado
i3blocks: commande introuvable
i3blocks: command not found
i3blocks: käsku ei ole
i3blocks: không tìm thấy lệnh
i3blocks: komanda nerasta
i3blocks: Kommando nicht gefunden.
i3blocks: kommandot finns inte
i3blocks: komut yok
i3blocks: nie znaleziono polecenia
i3blocks: níor aimsíodh an t-ordú
i3blocks: no se encontró la orden
i3blocks: no s'ha trobat l'ordre
i3blocks: opdracht niet gevonden
i3blocks: parancs nem található
i3blocks: perintah tidak ditemukan
i3blocks: príkaz nenájdený
i3blocks: příkaz nenalezen
i3blocks: команда не найдена
i3blocks: командата не е открита
i3blocks: 命令找不到
i3blocks: コマンドが見つかりません