sigtool: 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/sigtool - from package: clamav

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

On Debian possible default full paths are:

/usr/bin/sigtool - from package: clamav

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

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