icotool: 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/icotool - from package: icoutils

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

On Debian possible default full paths are:

/usr/bin/icotool - from package: icoutils

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

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