This is our second post on SED, which is a Stream EDitor. Please find our Previous post on SED. You can find our other posts on RegExp basics and extended.
Line number operator ( , and = switch)
We can search in a file according to line numbers.
Example13: Suppose I want to search in only 3rd line and then replace the term in that line alone.
sed ‘3 s/Surendra/bca/’ tem.txt
Example14:Search from 1st line to 4th line and replace that term.
sed ‘1,4 s/Surendra/bca/’ tem.txt
Example15:Search for a term from 3rd line to 5th line and replace it only between these lines.
sed ‘3,5 s/Surendra/bca/’ tem.txt
Example16:Search for a term from 2nd line to the end of the file and replace it with a term.
sed ‘2,$ s/Surendra/bca/’ tem.txt
Example17:How about combining two-line in to a single line. The below script will use N option which try to merge two, two lines in to single line and it will keep newline character in the combine line.
sed ‘N’ tem.txt
The output will not differ to the input file. If you want to really see the difference you have to use search and replace for n to some space or tab(t)
sed ‘N;s/n/ /’ tem.txt
surendra audi kumar nudi
mouni surendra baby dudy
Note:The above command is not used much of the time and I used this example to make it simple for below command for numbering.
Example18: I want to give numbering to all the lines after search and replace. Line numbers are given by using = option
sed = tem.txt
Example19: But is this right way to do the things? If I can display output as below that would be great.
1 surendra audi
2 kumar nudi
3 mouni surendra
4 baby dudy
To get above output we have to use N option to combine two lines
sed = tem.txt | sed ‘N;s/n/t/’
Search operator (/searcterm/)
Example20: sed can work for you on particular line where you given one word which is matching in that line. For example in fle tem.txt where ever it finds Surendra, replace audi with xyz. The code for that one is below
sed ‘/surendra/ s/audi/xyz/’ tem.txt
Example21: How about a range of lines, search for audi from first line to the search term Surendra and replace audi with xyz
sed ‘1,/Surendra/ s/audi/xyz/’ tem.txt
Example22: How about search from 3rd line to till it find Surendra?
sed ‘3,/Surendra/ s/audi/xyz/’ tem.txt
Example23: How about search and replace audi with xyz between two search terms Surendra and mouni?
sed ‘/Surendra/,/mouni/ s/audi/xyz/’ tem.txt
Example24: How about searching from a search pattern to end of the line?
sed ‘/Surendra/,$ s/audi/xyz/’ tem.txt
This operator will work with w, p and d options. We will see some examples below. This operator is bit confusing and require more practice to get more out of this.
This option is useful for negating the search pattern.
Example25: I want to display all the lines which do not contain abc word
sed –n ‘/abc/ !p’ tem.txt
Example26: I want to delete all lines expect the lines which contain surendra.
sed '/surendra/ !d' tem.txt
You can combine all the above mention techniques with this negation option.
Example27: What to delete all the lines expect 1 to 3
sed '1,3 !d'
SED scripting operator (-f switch)
This option is useful for writing complex SED script, as you people are aware of SED is one more scripting language such as Shell scripting, AWK and Perl etc.
sed -f sedscript.sed
Where sedscript.sed will contain SED script as we do for Bash scripting.
We are collecting SED onlines which are in net and going to explain them which are not explained in details for our readers.
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My name is Surendra Kumar Anne. I hail from Vijayawada which is capital of south Indian state of Andhra Pradesh. I am a Linux evangelist who believes in Hard work, A down to earth person, Likes to share knowledge with others, Loves dogs, Likes photography. I work with ICE systems, Sydney as Sr. Consultant. You can contact me at surendra (@) linuxnix dot com.