Linux : find

 find /usr/bin -name "ch*"

not like find/usr/bin -name ch*

// search a file based on the size.

find . -size -600c -ls  // less than 600bytes

find . -size +600c -ls // greater than 600bytes

find . -size 600c -ls // 600 bytes

b -> block

c -> bytes

k -> killo

w -> word