Issue
This is a very basic concept, but something I have never been able to articulate that well. and I would like to try to spell it and see where I go wrong.
If I have to, how would I define a "newline character". say if I create a new file in unix(or windows), then does the file store the "end of line" information by inserting a special character in the file called as "new line character". If so, what is its ascii value? I remember that in C programs, I have checked for the read character against the value '\n' . And why this confusing 2 characters to represent end of line characters..
bash$ cat states
California
Massachusetts
Arizona
Say, I want to insert one line space between the lines and want an output of the form: Desired output:
California
Massachusetts
Arizona
bash$sed -e 's/\n/\n\n/g' states does not work.
Why can't I treat "new line character" here just as I would treat any other character and run something like above command. (I understand that one might say that this is a matter of syntax of sed, but could one please explain the intuition behind not allowing this, so that I can get rid of my confusion.
Similarly, inside the vim editor, I can not use :%s/\n/\n\n/g . Why so?
Do I need to further escape \n by using a backslash in sed and from within vim?.
Thanks,
Jagrati
Solution
From the sed man page:
Normally, sed cyclically copies a line of input, not including its terminating newline character, into a pattern space, (unless there is something left after a "D" function), applies all of the commands with addresses that select that pattern space, copies the pattern space to the standard output, appending a newline, and deletes the pattern space.
It's operating on the line without the newline present, so the pattern you have there can't ever match. You need to do something else - like match against $ (end-of-line) or ^ (start-of-line).
Here's an example of something that worked for me:
$ cat > states
California
Massachusetts
Arizona
$ sed -e 's/$/\
> /' states
California
Massachusetts
Arizona
I typed a literal newline character after the \ in the sed line.
Answered By - Carl Norum Answer Checked By - Cary Denson (WPSolving Admin)
