sed commands

Eliminate comments

bash$ sed -e 's/#.*//' /etc/inetd

The substitute command:

s/re/repl/flags

flags is zero or more of the characters

g: substitute all matches of re
n: substitute the nth match
p: print the pattern buffer after a successful substitution
w file: If the substitution was made, then write out the result to the named file
I: GNU extension! match case-insensitive

s/// is not recursive

s/abc/abc/g

This is not a endless loop!

s/otto/o/g

The String "ottotto" will be changed to "otto", not to "o".