true: 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:

/bin/true - from package: coreutils

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

On Debian possible default full paths are:

/bin/true - from package: coreutils
/usr/lib/klibc/bin/true - from package: klibc-utils
/usr/lib/wims/bin/true - from package: wims

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

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