fidentify: 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
/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 CentOS possible default full paths are:

/usr/bin/fidentify - from package: testdisk

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/fidentify - from package: testdisk
/usr/lib/debug/usr/bin/fidentify - from package: testdisk-dbg

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