ldapmodify: 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 CentOS possible default full paths are:

/usr/bin/ldapmodify - from package: openldap-clients

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/ldapmodify - from package: ldap-utils

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

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