p7zipForFilemanager: 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
/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/p7zipForFilemanager - from package: p7zip-gui

You may install the required package with command yum install {package}
Error in other languages:
p7zipForFilemanager: bevel nie gevind nie
p7zipForFilemanager: comandă negăsită
p7zipForFilemanager: comando não encontrado
p7zipForFilemanager: commande introuvable
p7zipForFilemanager: command not found
p7zipForFilemanager: käsku ei ole
p7zipForFilemanager: không tìm thấy lệnh
p7zipForFilemanager: komanda nerasta
p7zipForFilemanager: Kommando nicht gefunden.
p7zipForFilemanager: kommandot finns inte
p7zipForFilemanager: komut yok
p7zipForFilemanager: nie znaleziono polecenia
p7zipForFilemanager: níor aimsíodh an t-ordú
p7zipForFilemanager: no se encontró la orden
p7zipForFilemanager: no s'ha trobat l'ordre
p7zipForFilemanager: opdracht niet gevonden
p7zipForFilemanager: parancs nem található
p7zipForFilemanager: perintah tidak ditemukan
p7zipForFilemanager: príkaz nenájdený
p7zipForFilemanager: příkaz nenalezen
p7zipForFilemanager: команда не найдена
p7zipForFilemanager: командата не е открита
p7zipForFilemanager: 命令找不到
p7zipForFilemanager: コマンドが見つかりません