# Linux – Is reading from /proc/sys/kernel/random/entropy_avail draining entropy

linuxrandom number generator

When I'm doing watch cat /proc/sys/kernel/random/entropy_avail, the amount of entropy steadily decreases, until I get about 150-200. Initially I get over 2000. When I stop reading that value and wait a minute or two, and then read it again, I am at about 2000 again. Why is reading that value reducing the entropy?

cat is a process, thus running watch cat ... will be consuming entropy constantly. Obviously, when you kill watch your system is restoring entropy to the usual level.