abipkgdiff: 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/abipkgdiff - from package: libabigail

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

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