Remove blank lines from a file using grep | UNIX | Tech-Recipes

Remove blank lines from a file using grep

Contributed by qmchenry

September 15, 2003

Tagged: UNIX

grep -v "^$" filename > newfilename

The ^$ within the quotes is a regular expression: ^=beginning of line, $=end of line, with no characters between.

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Anonymous 4 years ago 1 point
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From man grep:

<ul id="quote">The caret ^ and the dollar sign $ are metacharacters that respectively
match the empty string at the beginning and end of a line.</ul>
Not "$=beginning of line, ^=end of line"

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qmchenry 4 years ago 1 point
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Great catch! You are absolutely correct. The recipe has been repaired. Thank you for helping to improve Tech-Recipes.

Quinn

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raxxal 4 years ago 1 point
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By the way, if you want to see the $ sign, in vi enter :set list
also, in cat do the following: cat -vet

Raxxal

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Anonymous 4 years ago 1 point
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.. or, quicker, grep . <filename>

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Anonymous 10 months ago 1 point
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This wasn't working for me using Cygwin, then I realised that the file I was looking at had Windows line endings. There are any number of solutions to this, but the one I chose was to pipe through tr -d "r" before piping through grep. Then it worked like a charm. -- Richie Hindle, richie@entrian.com

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Anonymous 5 months ago 1 point
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The easiest way to remove blank lines from a file is to use a sed statement. The following syntax removes the blank lines.

# cat my_file | sed /^$/d

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