cgrfetch: 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/cgrfetch - from package: ion

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

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