How to install pgrep/pkill on debian wheezy docker image

Question

There is no pkill/pgrep in the base debian:wheezy docker image

# docker run debian:wheezy pkill 
System error: exec: "pkill": executable file not found in $PATH

and I can't figure out which package should I install to have these tools

# docker run debian:wheezy cat /etc/apt/sources.list
deb http://httpredir.debian.org/debian wheezy main
deb http://httpredir.debian.org/debian wheezy-updates main
deb http://security.debian.org wheezy/updates main
# docker run debian:wheezy apt-get install procps
E: Unable to locate package procps

Answer 1

Solved. I forgot about

apt-get update

before

apt-get install procps

in the container

Answer 2

try installing procps in your Dockerfile, or in your container, then commit it and launch the new image