Delete empty lines using sed

Question

I am trying to delete empty lines using sed   sed      d    but I have no luck with it   For example  I have these lines   xxxxxx   yyyyyy   zzzzzz   and I want it to be like   xxxxxx yyyyyy zzzzzz   What should be the code for this

User · Answer

With help from the accepted answer here and the accepted answer above, I have used:

$ sed 's/^ *//; s/ *$//; /^$/d; /^\s*$/d' file.txt > output.txt

`s/^ *//`  => left trim
`s/ *$//`  => right trim
`/^$/d`    => remove empty line
`/^\s*$/d` => delete lines which may contain white space

This covers all the bases and works perfectly for my needs. Kudos to the original posters @Kent and @kev

User · Answer

I am missing the awk solution   awk  NF  file   Which would return   xxxxxx yyyyyy zzzzzz   How does this work  Since NF stands for  number of fields   those lines being empty have 0 fiedls  so that awk evaluates 0 to False and no line is printed  however  if there is at least one field  the evaluation is True and makes awk perform its default action  print the current line

User · Answer

sed      d  should be fine  are you expecting to modify the file in place  If so you should use the -i flag   Maybe those lines are not empty  so if that s the case  look at this question Remove empty lines from txtfiles  remove spaces from start and end of line I believe that s what you re trying to achieve

User · Answer

This works in awk as well   awk         file xxxxxx yyyyyy zzzzzz

User · Answer

sed         space      d      s   d       d  -n     s    p    grep     -v      -v    s    -v      space         awk        NF   length        t      next    print          t

User · Answer

I believe this is the easiest and fastest one   cat file txt   grep     If you need to ignore all white-space lines as well then try this   cat file txt   grep   S    Example   s      a   b    Below is TAB         Below is space      c       echo   s    grep     wc -l  echo   s    grep   S    wc -l   outputs  7 5

User · Answer

You are most likely seeing the unexpected behavior because your text file was created on Windows  so the end of line sequence is  r n   You can use dos2unix to convert it to a UNIX style text file before running sed or use  sed -r     r   d    to remove blank lines whether or not the carriage return is there

User · Answer

You may have spaces or tabs in your  empty  line  Use POSIX classes with sed to remove all lines containing only whitespace   sed       space      d    A shorter version that uses ERE  for example with gnu sed   sed -r     s   d     Note that sed does NOT support PCRE

User · Answer

My bash-specific answer is to recommend using perl substitution operator with the global pattern g flag for this  as follows     perl -pe s    n        n  g   file xxxxxx yyyyyy zzzzzz   This answer illustrates accounting for whether or not the empty lines have spaces in them          as well as using   to separate multiple search terms fields  Tested on macOS High Sierra and CentOS 6 7   FYI  the OP s original code sed      d   file works just fine in bash Terminal on macOS High Sierra and CentOS 6 7 Linux at a high-performance supercomputing cluster

User · Answer

You can say   sed -n      p  filename     there is a space between

User · Answer

Another option without sed  awk  perl  etc  strings  file  gt   output   strings - print the strings of printable characters in files

User · Answer

You can do something like that using  grep   too   egrep -v      file txt

User · Answer

For me with FreeBSD 10 1 with sed worked only this solution    sed -e              d   testfile    inside    there are space and tab symbols   test file contains   fffffff next 1 tabline ffffffffffff  ffffffff next 1 Space line ffffffffffff  ffffffff empty 1 lines ffffffffffff               EOF

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