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I have a file that contains data including urls. But there are various lines which are not urls. How can I remove them using Ubuntu terminal commands?

Here is the Sample file for reference: Sample Data 

com.blendtuts/S
°=
com.blengineering.www/:http
±=

I want to have the output :

com.blendtuts/S
com.blengineering.www/:http

The extra unwanted lines do not have any dot. Hence, I want to remove the lines without dots

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6 Answers 6

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33

One way with sed

sed '/\./!d' file
  • /\./ match literal dot (escaped with \ because otherwise. matches any character)
  • !d delete everything except the matched pattern

If you want to edit the file in place, add -i to the command after testing. (You can also add .bak to the -i flag sed -i.bak ... to create a local backup of the file.) 

sed -i '/\./!d' file
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0
26

You could grep everything with a dot into a new file:

grep "\."  file > newfile

That way you can save your old file.

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10

Or keep the lines which contain a dot,

sed -ni.bak '/\./p' infile
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8

I think awk is that last one missing to the party:

$ awk -F\. 'NF>1' file
com.blendtuts/S
com.blengineering.www/:http

This sets the field separator to the dot. Then, it is a matter of printing those lines that have at least two fields: this will mean that at least one dot occurs.

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  • 3
    A simpler awk solution would be to do it in the same vein as grep: awk '/\./' file -- that is, to print only the lines containing the character '.'.
    – Chris Midgley
    Nov 8, 2016 at 13:05
  • @ChrisMidgley good one! Since this is what the answer with grep already suggested, I preferred to go with some awk-specific stuff :)
    – fedorqui
    Nov 8, 2016 at 13:43
6

Using perl:

perl -i -ne 'print if /\./' /path/to/file
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6

You can do this pretty easily with vim. If you are comfortable using vim as a text editor (opening, editing, and writing files), then do this:

:g!/\./d

If you are not comfortable using vim, or you would rather use it as a command-line tool, you may simply do from the terminal:

vim file -c "g!/\./d" -c "wq"

You could slightly modify this to save to a new file:

vim file -c "g!/\./d" -c "w newfile" -c "q!"

This uses vim's "global" command, which applies an ex command to every line matching (or not matching) a regex. In this case, the command is "(d)elete", and it will be applied to every command not matching the regex \.

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