Delete lines beginning with #

Question

How do I delete lines beginning with a #, given that there can be whitespace on the left and right of the #?

  # Master socket provides access to userdb information. It's typically

Answer 1

$ perl -pi -e '$_="" if /^\s*#/' filename

Answer 2

Using the sample data posted by ДМИТРИЙ МАЛИКОВ...

$ grep -vPh '^\s*#' filename.txt | grep -Po '\w+'
elephant
zoo
penguin

I prefer using pcre with grep so I use the -P switch for grep (must be GNU grep). The second grep is pure sugar to give you the words with no white-space. It would also "remove" empty lines.

Answer 3

perl -ne 'print if ! /^\s*#/' ./text

Answer 4

awk solution is to invert matching your pattern.

$> cat ./text
elephant
# Master socket provides access to userdb information. It's typically
zoo
 #ok
penguin
# !

$> awk '!/^(\ )*#/ {print $0}' ./text
elephant
zoo
penguin

Answer 5

This seems to work, but I've not given deep thought to it:

sed -e '/^[[:space:]]*#/d'

Answer 6

You can use grep for that

grep -vh '^[[:space:]]*#' filename

Since, as I presume, you are stripping comments from some file, you might also consider removing empty lines, which expands the above to:

grep -vh '^[[:space:]]*\(#\|$\)' filename