colmux: 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/colmux - from package: collectl

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

On Debian possible default full paths are:

/usr/bin/colmux - from package: collectl-utils

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

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