iinfo: 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/iinfo - from package: OpenImageIO-utils

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

On Debian possible default full paths are:

/usr/bin/iinfo - from package: openimageio-tools

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

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