git-rebase-theirs: 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 CentOS possible default full paths are:

/usr/bin/git-rebase-theirs - from package: git-tools

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