ldapmodifygroup: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/sbin/ldapmodifygroup - from package: ldapscripts

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