apertium-filter-ambiguity: 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-filter-ambiguity - from package: apertium

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

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