shntrim: 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/shntrim - from package: shntool

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

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