How to print a file by line range using sed?
Answer:
In a given file, if you want to print out, say line 340-350, is easy with sed:
# sed -n '340,350p' text.txt
Remove specified lines from a file using sed
Answer:
Assume your have a file text.txt contains 100 lines, if you want to remove the lines 20-30, what you need is sed:
# sed '20,30d' text.txt
That's is easy.
Insert search string back to the result in sed
Answer:
Following command will replace "foo" by "bar", using the sed.
# echo "foo" | sed 's/foo/bar/'
But how to append the word "foo" at the end of "bar"?
Here is the solution with the & (& defines the pattern found in the search string)
# echo "foo" | sed 's/foo/bar&/'
Speedup sed search and replace
Answer:
If you have a very large file, sometimes you can speed up sed by using the following method:
Original method:
# sed 's/foo/bar/g' filename
Optimized method:
# sed '/foo/ s/foo/bar/g' filename
The second method is faster since substitution is only performed when the search string is found.
Feb 082010
sed: replace in place
Answer:
Newer version of sed allow you replace a file in place, no more redirection is needed.
# sed -i 's/abc/def/g' test.txt
The above command will replace all "abc" to "def" in the file test.txt
