unixcat: 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/unixcat - from package: check-mk-livestatus

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

On Debian possible default full paths are:

/usr/bin/unixcat - from package: ucspi-unix

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

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