Remove blank lines with grep

Question

I tried grep -v      in Linux and that didn t work  This file came from a Windows file system

User · Answer

I tried hard  but this seems to work  assuming  r is biting you here    printf   r    egrep -xv     space

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grep -v      space        The -v makes it print lines that do not completely match     Each part explained                  match start of line    space      match whitespace- spaces  tabs  carriage returns  etc                previous match  whitespace  may exist from 0 to infinite times               match end of line   Running the code-    echo    gt  hello  gt          gt  ok     gt  grep -v      space       hello ok   To understand more about how why this works  I recommend reading up on regular expressions  http   www regular-expressions info tutorial html

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awk  NF  file-with-blank-lines  gt  file-with-no-blank-lines

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Use     dos2unix file   grep -v      file   Or just simply awk   awk  NF  file   If you don t have dos2unix  then you can use tools like tr   tr -d   r   lt    file   gt  t   mv t   file

User · Answer

It s true that the use of grep -v -e      can work  however it does not remove blank lines that have 1 or more spaces in them   I found the easiest and simplest answer for removing blank lines is the use of awk  The following is a modified a bit from the awk guys above    awk  NF  foo txt   But since this question is for using grep I m going to answer the following   grep -v        foo txt   Note  the blank space between the   and     Or you can use the  s to represent blank space like this   grep -v    s    foo txt

User · Answer

egrep -v     s s    egrep already do regex  and the  s is white space    The   duplicates current pattern   The   is for the start

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Using Perl   perl -ne  print if   S      S means match non-blank characters

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Use   grep pattern filename txt   uniq

User · Answer

The same as the previous answers   grep -v -e      foo txt   Here  grep -e means the extended version of grep       means that there isn t any character between   Start of line  and   end of line       and     are regex characters   So the command grep -v will print all the lines that do not match this pattern  No characters between   and      This way  empty blank lines are eliminated

User · Answer

Try the following   grep -v -e      foo txt   The -e option allows regex patterns for matching   The single quotes around    makes it work for Cshell  Other shells will be happy with either single or double quotes   UPDATE   This works for me for a file with blank lines or  all white space   such as windows lines with   r n  style line endings   whereas the above only removes files with blank lines and unix style line endings   grep -v -e      space       foo txt

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Keep it simple   grep   filename txt

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Do lines in the file have whitespace characters  If so then grep  quot  S quot  file txt Otherwise grep   file txt Answer obtained from  https   serverfault com a 688789

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If you have sequences of multiple blank lines in a row  and would like only one blank line per sequence  try  grep -v  unwantedThing  foo txt   cat -s   cat -s suppresses repeated empty output lines   Your output would go from  match1    match2   to  match1  match2   The three blank lines in the original output would be compressed or  squeezed  into one blank line

User · Answer

I prefer using egrep  though in my test with a genuine file with blank line your approach worked fine  though without quotation marks in my test   This worked too   egrep -v     r  n     filename txt

User · Answer

Here is another way of removing the white lines and lines starting with the   sign  I think this is quite useful to read configuration files    root localhost     cat  etc sudoers   egrep -v          Defaults    requiretty Defaults    visiblepw Defaults    always set home Defaults    env reset Defaults    env keep     COLORS DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR LS COLORS  root    ALL  ALL        ALL  wheel  ALL  ALL        ALL stack ALL  ALL  NOPASSWD  ALL

[text] Remove blank lines with grep

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