coqc: 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 Debian possible default full paths are:

/usr/bin/coqc - from package: coq

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

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