problem with sed

Kenhelm · 05-04-2010, 11:16 PM

Some ways of entering newlines in sed versions where \n doesn't work:-

"Frequently Asked Questions about sed, the stream editor.
4.1. How do I insert a newline into the RHS of a substitution?"
http://sed.sourceforge.net/sedfaq4.html#s4.1

eradev · 05-05-2010, 05:02 AM

Quote:

Originally Posted by petrus4

The sed answers are cool, and truthfully I didn't know you could use sed like that, but I would have used ed.

Code:

ed <file>
302i
This is the first line.
This is the second line.
This is the third line.
.
wq

It may seem strange, but I use ed quite a lot. I like it. I also feel that although it isn't really complicated, ed is sufficiently different to what you're used to, that if you want to learn to use it, you need to use it a lot in order to get familiar with it. Although I still use vi(m) for big files or longer edits, for me ed is very useful when I just want to do quick single line edits or search/replace for things; it's quicker than loading vi for that, and when you don't have to do much, the line addressing makes it a lot faster than vi's modal interface, as well.

Ed might also be better than sed in this case, because from what I've seen anywayz, sed isn't really designed to handle newlines. It can, but it's awkward.

Hello,

How can i use this in script? I want to write this three lines with script with variables.

eradev · 05-05-2010, 05:06 AM

Quote:

Originally Posted by petrus4

The sed answers are cool, and truthfully I didn't know you could use sed like that, but I would have used ed.

Code:

ed <file>
302i
This is the first line.
This is the second line.
This is the third line.
.
wq

It may seem strange, but I use ed quite a lot. I like it. I also feel that although it isn't really complicated, ed is sufficiently different to what you're used to, that if you want to learn to use it, you need to use it a lot in order to get familiar with it. Although I still use vi(m) for big files or longer edits, for me ed is very useful when I just want to do quick single line edits or search/replace for things; it's quicker than loading vi for that, and when you don't have to do much, the line addressing makes it a lot faster than vi's modal interface, as well.

Ed might also be better than sed in this case, because from what I've seen anywayz, sed isn't really designed to handle newlines. It can, but it's awkward.

Hello,

This example is for direct put in terminal. How can i use this in script? I want to write this three lines with script with variables like: ed $file $linei $text-line1 $text-line2....

sorry for my bad english :">

petrus4 · 05-05-2010, 05:58 AM

Quote:

Originally Posted by eradev

Hello,

This example is for direct put in terminal. How can i use this in script? I want to write this three lines with script with variables like: ed $file $linei $text-line1 $text-line2....

sorry for my bad english :">

That's ok. From memory ed can be used in scripts, but I'm not entirely sure how. For scripts, sed is probably going to work better.

MTK358 · 05-05-2010, 06:55 AM

Quote:

Originally Posted by eradev

sorry for my bad english :">

Your English is a pleasure compared to many other members here.

eradev · 05-05-2010, 07:13 AM

Quote:

Originally Posted by MTK358

Your English is a pleasure compared to many other members here.

Thank you

With this

Code:

sed -r '300 s:.*:&\nthis text will be inserted after line 300:'

is working, but i still cannot go to a new line. Everything is on same line. Do you know a way to pass a new line like pressing the button "enter"

crts · 05-05-2010, 08:28 AM

Quote:

Originally Posted by eradev

Thank you

With this

Code:

sed -r '300 s:.*:&\nthis text will be inserted after line 300:'

is working, but i still cannot go to a new line. Everything is on same line. Do you know a way to pass a new line like pressing the button "enter"

Hi,

I just noticed the windows logo on the left of your posts. Are you using sed for windows files? If so, then you might have to replace the '\n' with '\r\n'. Just a thought.

You might also want to try

Code:

sed -e '300 s/.*/&\
this text will be inserted after line 300/' infile

This also worked for me. Some older versions of sed have problems with a '\n' character on the right side of the substitution command.

eradev · 05-05-2010, 08:51 AM

Quote:

Originally Posted by crts

Hi,

I just noticed the windows logo on the left of your posts. Are you using sed for windows files? If so, then you might have to replace the '\n' with '\r\n'. Just a thought.

You might also want to try

Code:

sed -e '300 s/.*/&\
this text will be inserted after line 300/' infile

This also worked for me. Some older versions of sed have problems with a '\n' character on the right side of the substitution command.

I'm working on freebsd 7.2-release thro ssh.
Okay, do you know how i can with .sh script edit some line in file and insert 3 or 4 more lines with text on it?
say without sed..

MTK358 · 05-05-2010, 09:11 AM

AWK one-liner:

Code:

awk '{print; if (NR == 2) {print "this is\nsome text\ninserted after line 2."} }'

This was only tested on GNU awk, I can't guarantee it will work on FreeBSD's awk.

AWK script:

Code:

#!/bin/awk -f

{
	print
	if (NR == 2) # replace 2 with whatever line you want to insert text after
	{
		# an '\n' prints a newline. Note that a newline is automatically printed at the end
		print "this is\nsome text\ninserted after line 2."
	}
}'

eradev · 05-05-2010, 09:29 AM

Quote:

Originally Posted by MTK358

AWK one-liner:

Code:

awk '{print; if (NR == 2) {print "this is\nsome text\ninserted after line 2."} }'

This was only tested on GNU awk, I can't guarantee it will work on FreeBSD's awk.

AWK script:

Code:

#!/bin/awk -f

{
	print
	if (NR == 2) # replace 2 with whatever line you want to insert text after
	{
		# an '\n' prints a newline. Note that a newline is automatically printed at the end
		print "this is\nsome text\ninserted after line 2."
	}
}'

It's working! Thank you a lot man.

crts · 05-05-2010, 09:31 AM

Quote:

Originally Posted by eradev

I'm working on freebsd 7.2-release thro ssh.
Okay, do you know how i can with .sh script edit some line in file and insert 3 or 4 more lines with text on it?
say without sed..

Have you tried my suggestion in this post?
http://www.linuxquestions.org/questi...7/#post3955866
There sed is only used to split the file at insertion point. Afterwards three files are merged together, the middle one containing the lines you want to insert.

eradev · 05-05-2010, 10:40 AM

Quote:

Originally Posted by crts

Have you tried my suggestion in this post?
http://www.linuxquestions.org/questi...7/#post3955866
There sed is only used to split the file at insertion point. Afterwards three files are merged together, the middle one containing the lines you want to insert.

It's working, but how can i get this in .sh script with variables?
I had a problem with awk integrated in .sh script with variables.

MTK358 · 05-05-2010, 11:07 AM

Quote:

Originally Posted by eradev

I had a problem with awk integrated in .sh script with variables.

What problems exactly?

Where does the input come from (a variable, stdin, or a file) and where should the output go (a variable, stdout, or a file)?

If you can tell me that, I'll show you how to run AWK from your script appropriately.

eradev · 05-05-2010, 11:13 AM

Quote:

Originally Posted by MTK358

What problems exactly?

Where does the input come from (a variable, stdin, or a file) and where should the output go (a variable, stdout, or a file)?

If you can tell me that, I'll show you how to run AWK from your script appropriately.

something like that

Code:

/bin/cat $configfile | /usr/bin/awk '{print; if (NR == $startline) {print "$keyword\nmenu = $keyword1\ntitle = $keyword2 ($keyword3)\nhost = $keyword3\n"} }' > $tempconfigfile

without variables works great.

crts · 05-05-2010, 11:13 AM

Quote:

Originally Posted by eradev

It's working, but how can i get this in .sh script with variables?
I had a problem with awk integrated in .sh script with variables.

What are the variables? The text to be inserted? The files to be modified?