After a particular grep match, I want to transfer all the following contents of the file to another file

Question

I have a text file containing the following lines:

This is the first line
Second line
I have a mac
Used to have windows
Comfortable with both

So now I want to grep "I have a mac", and move all the contents that follow, into a new file. How do I do this? Thanks!

Answer 1

Crop everything from the line that contain "I have a mac" to the end of the file and write the output to a new file:

sed -n '/I have a mac/,$ p' in-file > out-file

Remove everything from the line that contain "I have a mac" to the end of the file, make the changes in place of the file and create a backup copy of the original file:

sed '/I have a mac/,$ d' in-file -i.bak

Use a variable that contain the string that you are searching for and conditionally execute the above two commands:

SEARCH='I have a mac'
sed -n "/$SEARCH/,$ p" in-file > out-file && sed "/$SEARCH/,$ d" in-file -i.bak

Use grep to find (recursively) which file(s) contains the searched string and pass its name through pipe and xargs to the above commands (reference):

export SEARCH='I have a mac'
grep -lr "$SEARCH" | xargs -L1 -I {} sh -c 'sed -n "/$SEARCH/,$ p" {} > {}.out && sed "/$SEARCH/,$ d" {} -i.bak'

Answer 2

With grep you could use -A switch ( --> After Context) and | tail -n+2 to start output with the second line to skip the match.

grep -A $(wc -l < file) mac file | tail -n+2

But using sed is probably better for this case:

sed '1,/mac/d' file

This deletes everything from first line (1) until and including the matching line.

or you could use awk:

awk '{if(m)print}/mac/{m=1}' file

will print a line when variable m is true if(m)print}, which is set to 1/true after the first match /mac/{m=1}.

---

"Transfer" stdout from a command to a file can be done with redirection: > another_file

sed '1,/mac/d' file > another_file
#or
awk '{if(m)print}/mac/{m=1}' file > another_file