niftiinfo: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/lib/voxbo/bin/niftiinfo - from package: voxbo

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