nifti2dicom: 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/nifti2dicom - from package: nifti2dicom

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

Error in other languages:
nifti2dicom: bevel nie gevind nie
nifti2dicom: comandă negăsită
nifti2dicom: comando não encontrado
nifti2dicom: commande introuvable
nifti2dicom: command not found
nifti2dicom: käsku ei ole
nifti2dicom: không tìm thấy lệnh
nifti2dicom: komanda nerasta
nifti2dicom: Kommando nicht gefunden.
nifti2dicom: kommandot finns inte
nifti2dicom: komut yok
nifti2dicom: nie znaleziono polecenia
nifti2dicom: níor aimsíodh an t-ordú
nifti2dicom: no se encontró la orden
nifti2dicom: no s'ha trobat l'ordre
nifti2dicom: opdracht niet gevonden
nifti2dicom: parancs nem található
nifti2dicom: perintah tidak ditemukan
nifti2dicom: príkaz nenájdený
nifti2dicom: příkaz nenalezen
nifti2dicom: команда не найдена
nifti2dicom: командата не е открита
nifti2dicom: 命令找不到
nifti2dicom: コマンドが見つかりません