comm: 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/comm - from package: coreutils

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

On Debian possible default full paths are:

/usr/bin/comm - from package: coreutils

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

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