fixrmtab: command not found

Have You tried accessing the binary with the full path?

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/sbin/fixrmtab - from package: am-utils

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