realpath: 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/libexec/TeXmacs/bin/realpath - from package: TeXmacs

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

On Debian possible default full paths are:

/usr/bin/realpath - from package: coreutils
/usr/lib/tiger/bin/realpath - from package: tiger

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

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