scotch_dgscat: 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/lib64/mpich/bin/scotch_dgscat - from package: ptscotch-mpich
/usr/lib/mpich/bin/scotch_dgscat - from package: ptscotch-mpich
/usr/lib64/openmpi/bin/scotch_dgscat - from package: ptscotch-openmpi
/usr/lib/openmpi/bin/scotch_dgscat - from package: ptscotch-openmpi

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

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