How to insert a newline in front of a pattern

Question

How to insert a newline before a pattern within a line   For example  this will insert a newline behind the regex pattern   sed  s regex  amp  n g    How can I do the same but in front of the pattern   Given this sample input file  the pattern to match on is the phone number   some text  012 345-6789   Should become  some text  012 345-6789

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In my case the below method works  sed -i  s playstation PS4   input txt  Can be written as  sed -i  s playstation PS4 nplaystation   input txt  PS4 playstation Consider using   n while using it in a string literal   sed   is stream editor  -i   Allows to edit the source file     Is delimiter    I hope the above information works for you

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Some of the other answers didn t work for my version of sed  Switching the position of  amp  and  n did work   sed  s regexp  n amp  g     Edit  This doesn t seem to work on OS X  unless you install gnu-sed

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This works in MAC for me  sed -i bak -e  s regex xregex g  input txt sed -i bak -e  s qregex      nregex g  input txt   Dono whether its perfect one

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In vi on Red Hat  I was able to insert carriage returns using just the  r character   I believe this internally executes  ex  instead of  sed   but it s similar  and vi can be another way to do bulk edits such as code patches   For example   I am surrounding a search term with an if statement that insists on carriage returns after the braces       s   my function       if  skip option   r t 1 r t     Note that I also had it insert some tabs to make things align better

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You can also do this with awk  using -v to provide the pattern   awk -v patt  pattern    0   patt  gsub patt    n patt  1  file   This checks if a line contains a given pattern  If so  it appends a new line to the beginning of it   See a basic example     cat file hello this is some pattern and we are going ahead bye    awk -v patt  pattern    0   patt  gsub patt    n patt  1  file hello this is some  pattern and we are going ahead bye    Note it will affect to all patterns in a line     cat file this pattern is some pattern and we are going ahead   awk -v patt  pattern    0   patt  gsub patt    n patt  1  d this  pattern is some  pattern and we are going ahead

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echo pattern   sed -E -e   s   pattern     n  1     worked fine on El Captitan with    support

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On my mac  the following inserts a single  n  instead of newline   sed  s regexp  n amp  g    This replaces with newline   sed  s regexp    echo -e   n r   g

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In sed  you can t add newlines in the output stream easily   You need to use a continuation line  which is awkward  but it works     sed  s regexp    amp      Example     echo foo   sed  s       amp     foo   See here for details   If you want something slightly less awkward you could try using perl -pe with match groups instead of sed     echo foo   perl -pe  s       n 1    foo    1 refers to the first matched group in the regular expression  where groups are in parentheses

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in sed you can reference groups in your pattern with   1     2        so if the pattern you re looking for is  PATTERN   and you want to insert  BEFORE  in front of it  you can use  sans escaping  sed  s  PATTERN  BEFORE 1 g    i e      sed  s   PATTERN   BEFORE 1 g

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You can use perl one-liners much like you do with sed  with the advantage of full perl regular expression support  which is much more powerful than what you get with sed    There is also very little variation across  nix platforms - perl is generally perl   So you can stop worrying about how to make your particular system s version of sed do what you want     In this case  you can do  perl -pe  s  regex   n 1     -pe puts perl into a  execute and print  loop  much like sed s normal mode of operation       quotes everything else so the shell won t interfere     surrounding the regex is a grouping operator    1 on the right side of the substitution prints out whatever was matched inside these parens       Finally   n is a newline   Regardless of whether you are using parentheses as a grouping operator  you have to escape any parentheses you are trying to match   So a regex to match the pattern you list above would be something like     d d d   d d d- d d d d      or    matches a literal paren  and  d matches a digit      Better      d 3    d 3 - d 4    I imagine you can figure out what the numbers in braces are doing   Additionally  you can use delimiters other than   for your regex   So if you need to match   you won t need to escape it   Either of the below is equivalent to the regex at the beginning of my answer   In theory you can substitute  any character for the standard   s     perl -pe  s  regex   n 1   perl -pe  s  regex    n 1     A couple final thoughts     using -ne instead of -pe acts similarly  but doesn t automatically print at the end   It can be handy if you want to print on your own   E g   here s a grep-alike  m foobar  is a regex match    perl -ne  if  m foobar    print     If you are finding dealing with newlines troublesome  and you want it to be magically handled for you  add -l   Not useful for the OP  who was working with newlines  though   Bonus tip - if you have the pcre package installed  it comes with pcregrep  which uses full perl-compatible regexes

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To insert a newline to output stream on Linux  I used   sed -i  s def abc   ndef   file1   Where file1 was   def   Before the sed in-place replacement  and   abc def   After the sed in-place replacement  Please note the use of    n  If the patterns have a   inside it  escape using

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sed -e  s regexp  0 n g     0 is the null  so your expression is replaced with null  nothing  and then     n is the new line     On some flavors of Unix doesn t work  but I think it s the solution to your problem   echo  Hello    sed -e  s Hello  0 ntmow g  Hello tmow

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Hmm  just escaped newlines seem to work in more recent versions of sed  I have GNU sed 4 2 1    dev   pg services places gt  echo  foobar    sed -r  s  bar   n 1    foo bar

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echo one two three   sed  s      g

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This works in bash and zsh  tested on Linux and OS X   sed  s regexp      n g    In general  for   followed by a string literal in single quotes bash performs C-style backslash substitution  e g     t  is translated to a literal tab  Plus  sed wants your newline literal to be escaped with a backslash  hence the   before    And finally  the dollar sign itself shouldn t be quoted so that it s interpreted by the shell  therefore we close the quote before the   and then open it again   Edit  As suggested in the comments by  mklement0  this works as well   sed   s regexp    n g    What happens here is  the entire sed command is now a C-style string  which means the backslash that sed requires to be placed before the new line literal should now be escaped with another backslash  Though more readable   in this case you won t be able to do shell string substitutions  without making it ugly again

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After reading all the answers to this question  it still took me many attempts to get the correct syntax to the following example script      bin bash   script  add domain   using fixed values instead of command line parameters  1   2   to show typical variable values in this example ipaddr  127 0 0 1  domain  example com    no need to escape  ipaddr and  domain values if we use separate quotes  sudo sed -i   a   n   ipaddr www  domain  domain   etc hosts   The script appends a newline  n followed by another line of text to the end of a file using a single sed command

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In this case  I do not use sed   I use tr   cat Somefile  tr       012     This takes the comma and replaces it with the carriage return

[shell] How to insert a newline in front of a pattern?

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