identify: 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/identify - from package: ImageMagick

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

On Debian possible default full paths are:

/usr/bin/identify - from package: graphicsmagick-imagemagick-compat

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

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