how can i append the text after pattern match using variable in sed

ravikushal · 07-23-2013, 07:01 AM

Hi,
I am new in sed scripting.I am trying to use sed in my bash script.Problem is below .
My file formate for file.txt is

hello linux
; Nodes
this is my first node
this is second
this is third one
this is fourth
;

I want to add some text after pattern " ; Nodes " .
The text i am going to add , that text i am reading from the user and storing in VARIABLE.
So how i can use this variable and append or insert the variable value after the " ; Nodes " pattern match .

I tried doing below but not working.

#!/bin/bash
variable=this is my top node
sed '/; Nodes/
n
a\$variable
}' file.txt

could anyone please help here ??
Thanks in advance. >> RaviKushal

Firerat · 07-23-2013, 07:08 AM

Code:

sed '/; Nodes/ a '"$variable"'' file.txt

druuna · 07-23-2013, 07:11 AM

Here is one way:

Code:

sed "s/^; Nodes/; Nodes\n$variable/" file.txt

Or using your script/sed solution:

Code:

#!/bin/bash

variable="this is my top node"

sed "/^; Nodes/a\
$variable" file.txt

I'm too slow.....

Firerat · 07-23-2013, 07:25 AM

Quote:

Originally Posted by druuna

I'm too slow.....

BUT Yours looks better than mine

Anyway, to insert before

Code:

sed '/; Nodes/ i '"$variable"'' file.txt

Actually,. just noticed something
I'm sure I've had to use 'newlines' in the past..
but don't seem to need them with sed (GNU sed) 4.2.2

ravikushal · 07-23-2013, 07:26 AM

HI druuna ,

i tried with ur first solution but its not changing anything in file.txt

logs

bash-3.2# ./scr.sh
hello linux
; Nodes
this is my first node
this is second
this is third one
this is fourth
;
bash-3.2# cat file.txt
hello linux
; Nodes
this is my first node
this is second
this is third one
this is fourth
;

ravikushal · 07-23-2013, 07:28 AM

HI druuna ,

i tried with ur second solution and its throwing

bash-3.2# ./scr.sh
sed: command garbled: /^; Nodes/athis is my top node
bash-3.2#

-------------------------------

Hi Firerat ,

the same garbled error trown by script.

Firerat · 07-23-2013, 07:30 AM

@ravikushal,

they both seem to be working well here.

Notice you have bash-3.2 ?
That is quite old ( but shouldn't be a problem here ), what version of sed do you have?

druuna · 07-23-2013, 07:33 AM

Did you put the content of variable between quotes?

WRONG: variable=this is my top node
CORRECT: variable="this is my top node"

It works on my side:

Code:

$ variable="this is my top node"
$ echo $variable
this is my top node
$ sed "s/^; Nodes/; Nodes\n$variable/" file.txt
hello linux
; Nodes
this is my top node
this is my first node
this is second
this is third one
this is fourth
;

Code:

$ cat file.sh 
#!/bin/bash

variable="this is my top node"

sed "/^; Nodes/a\
$variable" file.txt

$ ./file.sh 
hello linux
; Nodes
this is my top node
this is my first node
this is second
this is third one
this is fourth
;

ravikushal · 07-23-2013, 07:41 AM

i have a solaris machine , so My sed version i think

PKGINST: SUNWcsu
NAME: Core Solaris, (Usr)
CATEGORY: system
ARCH: i386
VERSION: 11.10.0,REV=2005.01.21.16.34

ravikushal · 07-23-2013, 07:44 AM

Hi druuna ,

Yes .

bash-3.2# cat scr.sh
#!/bin/bash

variable="this is my top node"

sed "/^; Nodes/a\
$variable" /SATY/file.txt
bash-3.2#
bash-3.2# ./scr.sh
sed: command garbled: /^; Nodes/athis is my top node
bash-3.2#

Firerat · 07-23-2013, 07:45 AM

Well, I think Druuna spotted it, see previous post.

druuna · 07-23-2013, 07:50 AM

You are using Solaris, which you should have mentioned in your first post.

I'm assuming you use the standard sed that comes with Solaris. But there are more versions available.

Try the one that resides in /usr/xpg4/bin

I.e.:

Code:

/usr/xpg4/bin/sed ..........

instead of

Code:

sed .......

Its been a while since I used Solaris, it could be that sed is located in /opt/sfw/bin/ instead (called gsed??).

ravikushal · 07-23-2013, 07:52 AM

Hello ,

i ran like below :

bash-3.2# variable="this is my top node"
bash-3.2# echo $variable
this is my top node
bash-3.2# sed "s/^; Nodes/; Nodes\n$variable/" file.txt
hello linux
; Nodes
this is my first node
this is second
this is third one
this is fourth
;
bash-3.2#

but still no change .
Its not working becuase the version which i have for bash and sed ??

ravikushal · 07-23-2013, 07:53 AM

Also any other way of doing this coding like using awk , or combination other cmd's ??

druuna · 07-23-2013, 07:56 AM

Edit: Misread the output. Sorry about that

If you need the original file to change then do the following:

Code:

sed "/^; Nodes/a\
$variable" file.txt > new.file.txt

mv new.file.txt file.txt

If you have a modern sed (version 4+) you can use the -i flag:

Code:

sed -i"/^; Nodes/a\
$variable" file.txt