apertium: 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 - from package: apertium

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

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