Using the command SED Post: 302588076

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Top Forums Shell Programming and Scripting Using the command SED Post 302588076 by tukuyomi on Friday 6th of January 2012 03:58:28 PM

01-06-2012

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Which system are you using? UNIX tool behave differently between systems

Quote:

Originally Posted by jyang72211

Question 1:
If I want to want replace the "search" string with "replace" string inside fileA. I understand that I can use

sed 's/search/replace' < fileA >fileB

I think you're missing the last slash. And if your sed takes files as argument, the `<` is useless:

Code:

sed 's/search/replace/' fileA >fileB

Quote:

Originally Posted by jyang72211

I also tried to do <fileA >fileA, but it doesn't work. Why is that? I don't want an extra file, fileB.

Try -i option:

Code:

sed -i 's/search/replace/' fileA

Quote:

Originally Posted by jyang72211

Question 2:
My main question. Inside the comand sed 's/search/replace' < fileA >fileB, the string "search" and "replaced" are actually inside fileC and fileD. How do I write the command? Thanks!

If fileC and fileD contain multiple search & replace patterns, you need to write a script that read each line in fileC and fileD to variables and use them in your sed command:

Code:

sed 's/'"$search"'/'"$replace"'/' fileA

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