Copy line to specific line number in a file

[alig...@gmail.com]

Hi,

I want to copy a line from a file to a specific line number in a file.

I copy line 3 from w.dat file to test.dat file using 

sed -n 3P w.dat >> test.dat

but it copy line 3 to the end of test.dat file, I want copy line 3 to line number 5 in the test.dat file, how can I do that? 

[Robert Citek]

Without example data, it's not completely clear what you are trying to do.  But this might be one of many ways to accomplish what you are trying to do:

$ { head -4 test.dat ; sed -n 3p w.dat ; tail -n +5 test.dat ; } | cat -n
     1 b1
     2 b2
     3 b3
     4 b4
     5 a3
     6 b5
     7 b6
     8 b7
     9 b8
    10 b9
    11 b10

Sample data:

$ paste w.dat test.dat  | cat -n
     1 a1 b1
     2 a2 b2
     3 a3 b3
     4 a4 b4
     5 a5 b5
     6 a6 b6
     7 a7 b7
     8 a8 b8
     9 a9 b9
    10 a10 b10

Regards,

- Robert

[alig...@gmail.com]

Hi Robert,

I want to copy line 5  from a file to line 3 in another file

Thanks in advance

[Robert Citek]

Hmm.  That sounds similar, but not identical to your original post. Can you clarify your question by giving an example, using a small dataset for both input and expected output? - Robert

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[alig...@gmail.com]

file 1 contains

da1

da2

da3

file 2 contains 

cx1

cx2

cx3

cx4

I want to copy da2 after cx2, I want output will be

cx1

cx2

da2

cx3

cx4

[Robert Citek]

Input files:

$ cat file1
da1
da2
da3

$ cat file2
cx1
cx2
cx3
cx4

Pick just the lines you want from each file:

$ head -2 file2
cx1
cx2

$ sed -n 2p file1
da2

$ tail +3 file2
cx3
cx4

Stitch the commands together with braces to achieve your output:

$ {
  head -2 file2
  sed -n 2p file1
  tail +3 file2

}
cx1
cx2
da2
cx3
cx4

Regards,

- Robert

To view this discussion on the web visit https://groups.google.com/d/msgid/linuxusersgroup/66073c9a-2082-47c1-a2f2-d4d352fab537n%40googlegroups.com.

[alig...@gmail.com]

Thanks for your help, but tail +3 appears an error as

$ tail: cannot open '+3' for reading: No such file or directory

[Robert Citek]

Your version of tail may require a '-n' option, that is:

tail -n +3 file2

Regards,

- Robert

To view this discussion on the web visit https://groups.google.com/d/msgid/linuxusersgroup/6d401d19-f638-40ac-99f5-803c8b5ec7abn%40googlegroups.com.

[alig...@gmail.com]

Thank you Robert

[Robert Citek]

Have a look at the syntax for a 'for' loop.

$ help for
for: for NAME [in WORDS ... ;] do COMMANDS; done
    The `for' loop executes a sequence of commands for each member in a
    list of items.  If `in WORDS ...;' is not present, then `in "$@"' is
    assumed.  For each element in WORDS, NAME is set to that element, and
    the COMMANDS are executed.

Regards,

- Robert

On Tue, Jan 5, 2021 at 1:48 AM alig...@gmail.com <alig...@gmail.com> wrote:

Dear Robert,

I want to make iteration with line number as 

 

for j in 1 2 3

sed -n $jp file.dat

done

but the following error appears

$ syntax error near unexpected token `sed'

I tried to put space between $j and p but not works.

how I can do it?

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