coinst_viewer: 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/coinst_viewer - from package: coinst-viewer

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

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