expeyes-doc: 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/expeyes-doc - from package: expeyes-doc-common

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

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