zkEnv.sh: 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
/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/zkEnv.sh - from package: zookeeper

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