exiftool: 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 CentOS possible default full paths are:

/usr/bin/exiftool - from package: perl-Image-ExifTool

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

On Debian possible default full paths are:

/usr/bin/exiftool - from package: libimage-exiftool-perl

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

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