Comment out every line in a file

From raju

Description

The idea here is to comment out every line in a file. Consider for example

$cat foo.txt
foo
bar
baz
qux
quux

We want

# foo
# bar
# baz
# qux
# quux

Solution using awk

$awk '{printf "# "; print}' foo.txt
# foo
# bar
# baz
# qux
# quux

Solution using sed

$sed -e 's/^/# /g' foo.txt
# foo
# bar
# baz
# qux
# quux

You can also do

$sed -e 's/\(.*\)/# \1/g' foo.txt
# foo
# bar
# baz
# qux
# quux


To comment out only some lines but not all

$sed -e '2,4s/^/# /g' foo.txt
foo
# bar
# baz
# qux
quux

tags | prepend each line with something

Ref: