Strip comments from a file

introuble · 09-30-2006, 02:08 AM

I have a file, config.cfg. All lines beginning with "#" are comments (whilst a line of the form:

Code:

aaa # something

is not.). I need to strip all comments from the file from the bash prompt. Any ideas?

ghostdog74 · 09-30-2006, 02:23 AM

an sed/awk solution will be posted soon enough, but i like to do it in Python

Code:

#!/usr/bin/python
import fileinput
for lines in fileinput.FileInput("data.bak",1): #inplace edit
 	lines = lines.strip() #strip newlines
 	if lines.startswith("#"):
 		lines = lines[1:]
 	print lines

spirit receiver · 09-30-2006, 05:28 AM

But here's sed:

Code:

sed -i.bak -e '/^#/d' filename

It makes a backup of the original file.

////// · 09-30-2006, 09:23 AM

Code:

grep -v '^#'

Delete lines beginning with a hashmark.

Edit:

Code:

grep -v '^$'

This one for blank lines.

homey · 09-30-2006, 10:40 AM

I was working on a python oneliner but, I don't know how to tell it only comments at the beginning of lines. Waiting for python guru input.

Code:

python -c "import sys; print sys.stdin.read().replace('#', '')," < file.txt

bulliver · 09-30-2006, 10:51 AM

I wrote this a while ago:
http://badcomputer.org/unix/code/cfgcl.bot

Dan04 · 09-30-2006, 12:39 PM

Quote:

Originally Posted by homey

I was working on a python oneliner but, I don't know how to tell it only comments at the beginning of lines. Waiting for python guru input.

Code:

python -c "import sys; sys.stdout.writelines(line for line in sys.stdin if not line.strip().startswith('#'))" < file.txt

homey · 09-30-2006, 12:56 PM

Thanks Dan04!

BCarey · 09-30-2006, 03:29 PM

Or with perl:

Code:

perl -n -i.bak -e "print unless /^#/;" test.dat

This one also creates a backup.

Brian

jim mcnamara · 10-02-2006, 05:05 PM

Code:

sed 's/#.*//;/^$/d' filename > newfilename