Insert multiple lines into a file after specified pattern using shell script

Question

I want to insert multiple lines into a file using shell script  Let us consider my input file contents are  input txt   abcd accd cdef line web   Now I have to insert four lines after the line  cdef  in the input txt file  After inserting my file should change like this   abcd accd cdef line1 line2 line3 line4 line web   The above insertion I should do using the shell script  Can any one help me

User · Accepted Answer

Another sed   sed   cdef r add txt  input txt   input txt   abcd accd cdef line web   add txt   line1 line2 line3 line4   Test   sat    sed   cdef r add txt  input txt abcd accd cdef line1 line2 line3 line4 line web   If you want to apply the changes in input txt file  Then  use -i with sed   sed -i   cdef r add txt  input txt   If you want to use a regex as an expression you have to use the -E tag with sed   sed -E   RegexPattern r add txt  input txt

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I needed to template a few files with minimal tooling and for me the issue with above sed -e      r file txt is that it only appends the file after it prints out the rest of the match  it doesn t replace it   This doesn t do it  all matches are replaced and pattern matching continues from same point      bin bash  TEMPDIR   mktemp -d    TMPDIR - tmp    basename  0  XXXXXXXXXXXX     remove on exit trap  rm -rf  TEMPDIR  EXIT  DCTEMPLATE  TEMPDIR dctemplate txt DCTEMPFILE  TEMPDIR dctempfile txt    template that will replace printf  0replacement 1  SHELL  data 2anotherlinenoEOL   gt   DCTEMPLATE    test data echo -e  xxy  n987  nxx xx n yz yxxyy   gt   DCTEMPFILE    print original for debug echo  ---8 lt ---  DCTEMPFILE  cat  DCTEMPFILE echo  ---8 lt ---  DCTEMPLATE  cat  DCTEMPLATE echo  ---8 lt ---     replace  xx  - gt  contents of  DCTEMPFILE perl -e  our   fname      DCTEMPLATE     -pe  s xx  cat  fname  eg    DCTEMPFILE

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Using awk   awk   cdef  print  0 RS  line1  RS  line2  RS  line3  RS  line4  next 1  input txt    Explanation    You find the line you want to insert from using       You print the current line using print  0 RS is built-in awk variable that is by default set to new-line   You add new lines separated by this variable 1 at the end results in printing of every other lines  Using next before it allows us to prevent the current line since you have already printed it using print  0         awk   cdef  print  0 RS  line1  RS  line2  RS  line3  RS  line4  next 1  input txt abcd accd cdef line1 line2 line3 line4 line web     To make changes to the file you can do   awk       input txt  gt  tmp  amp  amp  mv tmp input txt

User · Answer

Here is a more generic solution based on  rindeal solution  which does not work on MacOS BSD   r expects a file    cat  lt  lt  DOC  gt  input txt abc cdef line DOC     cat  lt  lt  EOF   sed    cdef   r  dev stdin  input txt line 1 line 2 EOF    outputs  abc cdef line 1 line 2 line   This can be used to pipe anything into the file at the given position     date   sed    cdef   r  dev stdin  input txt    outputs abc cdef Tue Mar 17 10 50 15 CET 2020 line   Also  you could add multiple commands which allows deleting the marker line cdef     date   sed    cdef       r  dev stdin   d    input txt    outputs abc Tue Mar 17 10 53 53 CET 2020 line

User · Answer

Using GNU sed   sed   cdef aline1 nline2 nline3 nline4  input txt   If you started with   abcd accd cdef line web   this would produce   abcd accd cdef line1 line2 line3 line4 line web   If you want to save the changes to the file in-place  say   sed -i   cdef aline1 nline2 nline3 nline4  input txt

User · Answer

sed    cdef  r  lt       echo  line1      echo  line2      echo  line3      echo  line4    -i -- input txt

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You can use awk for inserting output of some command in the middle of input txt  The lines to be inserted can be the output of a cat otherfile  ls -l or 4 lines with a number generated by printf   awk  NR  FNR  a NR   0 next       print       cdef   for  i 1  i  lt   length a   i      print a i           lt  printf   s n  line 1  4   input txt

User · Answer

if you want to do that with a bash script  that s useful  echo  password   echo  net ipv4 ping group range 0 2147483647     sudo -S tee -a  etc sysctl conf

User · Answer

This answer is easy to understand   Copy before the pattern  Add your lines  Copy after the pattern Replace original file  FILENAME  app Providers AuthServiceProvider php    STEP 1 copy until the pattern  sed   THEPATTERNYOUARELOOKINGFOR Q   FILENAME  gt  gt   FILENAME  temp   STEP 2 add your lines  cat  lt  lt   EOL   gt  gt    FILENAME  temp  HERE YOU COPY AND PASTE MULTIPLE LINES  ALSO YOU CAN   WRITE COMMENTS  AND NEW LINES AND SPECIAL CHARS LIKE  THISONE  EOL   STEP 3 add the rest of the file  grep -A 9999  THEPATTERNYOUARELOOKINGFOR   FILENAME  gt  gt   FILENAME  temp   REPLACE original file  mv   FILENAME  temp  FILENAME   if you need variables  in step 2 replace  EOL  with EOL  cat  lt  lt  EOL  gt  gt    FILENAME  temp  this variable will expand   variable1  EOL

[linux] Insert multiple lines into a file after specified pattern using shell script

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