eiskaltdcpp-cli-jsonrpc: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/eiskaltdcpp-cli-jsonrpc - from package: eiskaltdcpp-cli

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