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Ignore Lines Begining With #

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# 1  
Old 08-18-2005
Ignore Lines Begining With #
Is there a standard way to make a shell script read a file, or list, and skip each line that contains # at the begining, or ignores the content starting after a # in line?

I'm looking to mimic the way commenting in a shell script normally works. This way I can comment my text files and lists my scripts process and ignore comment lines.

Thanks guys. Smilie
# 2  
Old 08-18-2005
If you want to do only a couple things with the output, filter you source file in a pipeline:
Code:
grep -v '^[[:space:]]*#' /path/to/your/file | your_commands

if you want do extensive stuff with your comment-stripped file, save the stripped file in a temp file, and use use the temp file for the rest of the procedure:
Code:
grep -v '^[[:space:]]*#' /path/to/your/file  >/tmp/stripped_source

Note that I use ^[[:space:]]* at the start of the regular expression because lines that are completely comments can still contain leading whitespace. If you want to eliminate blank lines also, do
Code:
 egrep -v '(^[[:space:]]*#|^[[:space:]]*$)' /path/to/file >/tmp/stripped_file

Last edited by hadarot; 08-18-2005 at 09:53 PM..
# 3  
Old 08-18-2005
Try...
Code:
$ cat file1
#line1
  #line2
line#3
line4

$ sed '/^ *#/d;s/#.*//' file1
line
line4

# 4  
Old 08-22-2005
Quote:
Originally Posted by Ygor
Try...
Code:
$ cat file1
#line1
  #line2
line#3
line4

$ sed '/^ *#/d;s/#.*//' file1
line
line4

After some testing I went with this method. Thanks to both of you. Smilie
# 5  
Old 08-23-2005
If you want your script to behave like the ksh itself (ignore the part of a line after a "#" but use the part before it) you could do the following (replace "<spc>" with a literal space, "<tab>" with a tab char):

Code:
script

sed 's/#.*$/;s/^[<spc><tab>]*//;s/[<spc><tab>]*$//;/^$/d' file

content of file
# this is a line with comments
   # this too, but starting with blanks
command 1        # this line contains an inline comment

command 2 "#"   # this too, but my script would be confused

result
command 1
command 2 "

Alas, the script fails on the second line, but save for such delicacies it works.

bakunin
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