Find text in a file and copy it to another file

Question

Is there any command in Linux to find text in a file and if found then copy it in another file?

Using sed -i we can find text but how to copy whole line in another file?

Solution 1

Don't use sed -i - it would overwrite your original file.

Use grep instead.

grep "text to find" input.txt > output.txt

Solution 2

As I understand the question, the op wants to find the text and put it in another file, not the whole line which the text was found.

I would use the grep -o 'pattern' input_file > output_file.

The -o flag:

-o, --only-matching
       Print  only  the  matched  (non-empty) parts of a matching line, 
       with each such part on a separateoutput line.

---

Example:

$ cat tmp
01/21/21 - foo
01/22/21 - bar
01/23/21 - foo
01/24/21 - bar

$ grep -o 'foo' tmp > foo

$ cat foo
foo
foo

Solution 3

sed outputs to stdout by default. To output to a file, redirect sed's stdout to a file using the > operator (if you want to create a new file) or using the >> operator (if you want to append the output to an already existing file):

sed '/text/' inputfile > outputfile
sed '/text/' inputfile >> outputfile