zkCli.sh: 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/share/zookeeper/bin/zkCli.sh - from package: zookeeper

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

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