Insert a line at specific line number with sed or awk

Question

I have a script file which I need to modify with another script to insert a text at the 8th line   String to insert  Project Name sowstest  into a file called start   I tried to use awk and sed  but my command is getting garbled

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the awk answer  awk -v n 8 -v s  Project Name sowstest   NR    n  print s   print   file  gt  file new

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sed -i  quot  quot  -e   4 a  n  Project Name sowstest  start  This line works fine in macOS

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POSIX sed  and for example OS X s sed  the sed below  require i to be followed by a backslash and a newline  Also at least OS X s sed does not include a newline after the inserted text     seq 3 gsed  2i1 5  1 1 5 2 3   seq 3 sed  2i1 5  sed  1   2i1 5   command i expects   followed by text   seq 3 sed   2i   n1 5  1 1 52 3   seq 3 sed   2i   n1 5 n  1 1 5 2 3   To replace a line  you can use the c  change  or s  substitute  commands with a numeric address     seq 3 sed   2c   n1 5 n  1 1 5 3   seq 3 gsed  2c1 5  1 1 5 3   seq 3 sed  2s    1 5   1 1 5 3   Alternatives using awk     seq 3 awk  NR  2 print 1 5 1  1 1 5 2 3   seq 3 awk   print NR  2 1 5  0   1 1 5 3   awk interprets backslashes in variables passed with -v but not in variables passed using ENVIRON     seq 3 awk -v v  a ba    print NR  2 v  0   1 a 3   seq 3 v  a ba  awk   print NR  2 ENVIRON  v    0   1 a ba 3   Both ENVIRON and -v are defined by POSIX

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For those who are on SunOS which is non-GNU  the following code will help   sed  1i  J line to add  test dat  gt  tmp dat     J is inserted with  V  J Add the newline after  1i    MUST be the last character of the line  The second part of the command must be in a second line

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An ed answer  ed file  lt  lt  END 8i Project Name sowstest   w q END     on its own line ends input mode  w writes  q quits  GNU ed has a wq command to save and quit  but old ed s don t    Further reading  https   gnu org software ed manual ed manual html

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OS X   macOS   FreeBSD sed  The -i flag works differently on macOS sed than in GNU sed    Here s the way to use it on macOS   OS X   sed -i     8i  8 This is Line 8  FILE   See man 1 sed for more info

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Perl solutions   quick and dirty   perl -lpe  print  Project Name sowstest  if       8  file   -l strips newlines and adds them back in  eliminating the need for   n  -p loops over the input file  printing every line -e executes the code in single quotes      is the line number  equivalent to  glenn s awk solution  using named arguments   perl -slpe  print  s if        n  -- -n 8 -s  Project Name sowstest  file   -s enables a rudimentary argument parser -- prevents -n and -s from being parsed by the standard perl argument parser   positional command arguments   perl -lpe  BEGIN  n shift   s shift   print  s if        n  8  Project Name sowstest  file  environment variables   setenv n 8   setenv s  Project Name sowstest  echo  n   echo  s perl -slpe  print  ENV s  if        ENV n   file   ENV is the hash which contains all environment variables  Getopt to parse arguments into hash  o   perl -MGetopt  Std -lpe  BEGIN getopt  ns    o    print  o s  if        o n   -- -n 8 -s  Project Name sowstest  file  Getopt  Long and longer option names  perl -MGetopt  Long -lpe  BEGIN GetOptions   o  line i   string s     print  o string  if        o line   -- --line 8 --string  Project Name sowstest  file  Getopt is the recommended standard-library solution  This may be overkill for one-line perl scripts  but it can be done

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sed -e  8iProject Name sowstest  -i start using GNU sed  Sample run    root node23     for   i 1  i lt  10  i      do echo  Line   i   done  gt  a file  root node23     cat a file Line  1 Line  2 Line  3 Line  4 Line  5 Line  6 Line  7 Line  8 Line  9 Line  10  root node23     sed -e  3ixxx inserted line xxx  -i a file   root node23     cat -An a file       1  Line  1       2  Line  2       3  xxx inserted line xxx       4  Line  3       5  Line  4       6  Line  5       7  Line  6       8  Line  7       9  Line  8      10  Line  9      11  Line  10   root node23       root node23     sed -e  5ixxx  inserted   line  xxx  -i a file  root node23     cat -n a file       1  Line  1      2  Line  2      3  xxx inserted line xxx      4  Line  3      5  xxx  inserted   line  xxx      6  Line  4      7  Line  5      8  Line  6      9  Line  7     10  Line  8     11  Line  9     12  Line  10  root node23

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sed -i  8i8 This is Line 8  FILE   inserts at line 8  8 This is Line 8   into file FILE   -i does the modification directly to file FILE  no output to stdout  as mentioned in the comments by glenn jackman

[sed] Insert a line at specific line number with sed or awk

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