Showing posts with label blank. Show all posts
Showing posts with label blank. Show all posts
Tuesday, February 18, 2014
How to remove comments and blank lines from file
So often you need to remove comments and blank lines form configuration files.
You can do it in a very easy single step.
#grep -v ^$ file.conf | grep -v ^#
What it does is grep ^$ from your file. You must be saying I dont have any such character in my file. Actually those characters have their own meaning.
^ begging of the line
$ end of the line
So searching for ^$ means you are searching a blank line.
The -v option invert your search.
So #grep -v ^$ matches all the lines except the blank lines.
Again the pipe | sends those match to another grep command which matches any line begging with #. Then -v option again inverts the match giving you all the lines except comment and blank lines.
If you want the output in a file rather than screen then redirect it,
#grep -v ^$ file.conf | grep -v ^# > newfile
For more of the input/output and error redirection visit http://.blogspot.com/2008/06/devnull-2.html
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You can do it in a very easy single step.
#grep -v ^$ file.conf | grep -v ^#
What it does is grep ^$ from your file. You must be saying I dont have any such character in my file. Actually those characters have their own meaning.
^ begging of the line
$ end of the line
So searching for ^$ means you are searching a blank line.
The -v option invert your search.
So #grep -v ^$ matches all the lines except the blank lines.
Again the pipe | sends those match to another grep command which matches any line begging with #. Then -v option again inverts the match giving you all the lines except comment and blank lines.
If you want the output in a file rather than screen then redirect it,
#grep -v ^$ file.conf | grep -v ^# > newfile
For more of the input/output and error redirection visit http://.blogspot.com/2008/06/devnull-2.html
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