sqlt-diff-old: 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/sqlt-diff-old - from package: perl-SQL-Translator

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

On Debian possible default full paths are:

/usr/bin/sqlt-diff-old - from package: libsql-translator-perl

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

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