NIfTI1ToDicom: 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/NIfTI1ToDicom - from package: pixelmed-apps

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

Error in other languages:
NIfTI1ToDicom: bevel nie gevind nie
NIfTI1ToDicom: comandă negăsită
NIfTI1ToDicom: comando não encontrado
NIfTI1ToDicom: commande introuvable
NIfTI1ToDicom: command not found
NIfTI1ToDicom: käsku ei ole
NIfTI1ToDicom: không tìm thấy lệnh
NIfTI1ToDicom: komanda nerasta
NIfTI1ToDicom: Kommando nicht gefunden.
NIfTI1ToDicom: kommandot finns inte
NIfTI1ToDicom: komut yok
NIfTI1ToDicom: nie znaleziono polecenia
NIfTI1ToDicom: níor aimsíodh an t-ordú
NIfTI1ToDicom: no se encontró la orden
NIfTI1ToDicom: no s'ha trobat l'ordre
NIfTI1ToDicom: opdracht niet gevonden
NIfTI1ToDicom: parancs nem található
NIfTI1ToDicom: perintah tidak ditemukan
NIfTI1ToDicom: príkaz nenájdený
NIfTI1ToDicom: příkaz nenalezen
NIfTI1ToDicom: команда не найдена
NIfTI1ToDicom: командата не е открита
NIfTI1ToDicom: 命令找不到
NIfTI1ToDicom: コマンドが見つかりません