ipcs: 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/ipcs - from package: util-linux-ng

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

On Debian possible default full paths are:

/usr/bin/ipcs - from package: util-linux

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

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