apertium-rewxml: 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 Debian possible default full paths are:

/usr/bin/apertium-rewxml - from package: apertium

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

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