Ignore Lines Begining With # - Shell Programming and Scripting

sysera · #1 08-18-2005

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.

hadarot · #2 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

Ygor · #3 08-18-2005

Try...

Code:

$ cat file1
#line1
  #line2
line#3
line4

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

sysera · #4 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.

bakunin · #5 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

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
awk, ignore first x number of lines.	trey85stang	Shell Programming and Scripting	8	05-21-2008 01:44 AM
Ignore some lines with specific words from file comparison	jakSun8	Shell Programming and Scripting	2	03-12-2008 09:11 PM
How can I ignore only the lines which have # at the begining?	csaha	Shell Programming and Scripting	1	01-30-2006 12:35 AM
Make sed ignore lines	Scarlos	Shell Programming and Scripting	2	07-21-2005 07:33 AM
Removing duplicate lines ignore case	hellsd	UNIX for Dummies Questions & Answers	17	12-02-2004 07:47 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode