2

I have tried the following command:-

[root@10 bin]# cat temp
asdjahskjdhajksdhjkashjahfksjdhfkjsddhflkdsjhfklsdajhfklajshdkjalsdlkjasdhkljas
hskdajkdhkjas
 cast $recv $UE_CAPABILITY_ENQUIRY
                set trans_id [ string range $recv 42 43 ]

[root@10 bin]# sed -ir '/^cast \$recv \$UE_CAPABILITY_ENQUIRY$/{$!{N;s/^cast \$recv \$UE_CAPABILITY_ENQUIRY\nset trans_id \[ string range \$recv 42 43 \]$/cast \$recv \$UE_CAPABILITY_ENQUIRY \nset trans_id 1/;ty;P;D;:y}}' temp

I want to replace 

 cast $recv $UE_CAPABILITY_ENQUIRY
                set trans_id [ string range $recv 42 43 ]

with 

cast $recv $UE_CAPABILITY_ENQUIRY
                set trans_id 1

But above command is not working. Can some body point out my mistake.

Improve this question
6
  • why would you replace multiline ? as 1st line remains unchanged, only text after trans_id is replacing ? Commented Jun 17, 2016 at 9:40
  • @Rahul I'm assuming it's because the rest of the file (the garbage in the example) might be a script with lines that identical to the line he wants to modify, but with different preceding lines. Is that so @PriyatoshRai? Commented Jun 17, 2016 at 9:43
  • 1
    Hi, Actually there are multiple occurence of "set trans_id [ string range $recv 42 43 ]" line in a file but i need to replace only the lines just after cast $recv $UE_CAPABILITY_ENQUIRY. yes garbage is just for example Commented Jun 17, 2016 at 9:45
  • @PriyatoshRai, please update the question with this info! Commented Jun 17, 2016 at 9:51
  • 1
    Possible duplicate of Replace a long string with the sed command: Argument list too long error Commented Jun 18, 2016 at 2:27

1 Answer 1

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3

Since you're not actually changing the "cast" line:

sed '/cast \$recv \$UE_CAPABILITY_ENQUIRY/{a\
                set trans_id 1
n;d}' file

As Kusalananda comments, this command:

  • when one of the wanted "cast" lines is found:
    • append the new line
    • take the next line from the file (the unwanted "set" line)
    • and delete it

In hindsight, this does not confirm that the delete line is the one you want to delete. I would change this to:

sed '
    /cast \$recv \$UE_CAPABILITY_ENQUIRY/ {
        n
        /set trans_id \[ string range \$recv 42 43 \]/ {
            i\
                set trans_id 1
            d
        }
    }
' file

For files recursively:

find . type f | xargs sed -i '' -e '...'

With GNU tools, more safely

find . type f -print0 | xargs -0 sed -i '' -e '...'
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2
  • 2
    I understand this because I know sed, but it may be unintuitive for others. You're matching the line that need to be preceding the affected line. Once this is found, you simply add the wanted contents to the output and skip to reading the next line, which you delete (because it's being replaced). Commented Jun 17, 2016 at 10:47
  • @glenn jackman Thanku so much , if i need to do these for all the files recursively:- sed -i '' -e '/cast \$recv \$UE_CAPABILITY_ENQUIRY/{a\ set trans_id 1 n;d}' $(find . -type f) But this is not working Commented Jun 17, 2016 at 11:33

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