abidiff: 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/abidiff - from package: libabigail

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

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