sim_c: 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/sim_c - from package: similarity-tester

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

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