oiiotool: 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/oiiotool - from package: OpenImageIO-utils

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

On Debian possible default full paths are:

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

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

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