How to copy the first few lines of a giant file, and add a line of text at the end of it using some Linux commands?
LinuxLinux Problem Overview
How do I copy the first few lines of a giant file and add a line of text at the end of it, using some Linux commands?
Linux Solutions
Solution 1 - Linux
The head command can get the first n lines. Variations are:
head -7 file
head -n 7 file
head -7l file
which will get the first 7 lines of the file called "file". The command to use depends on your version of head. Linux will work with the first one.
To append lines to the end of the same file, use:
echo 'first line to add' >>file
echo 'second line to add' >>file
echo 'third line to add' >>file
or:
echo 'first line to add
second line to add
third line to add' >>file
to do it in one hit.
So, tying these two ideas together, if you wanted to get the first 10 lines of the input.txt file to output.txt and append a line with five "=" characters, you could use something like:
( head -10 input.txt ; echo '=====' ) > output.txt
In this case, we do both operations in a sub-shell so as to consolidate the output streams into one, which is then used to create or overwrite the output file.
Solution 2 - Linux
I am assuming what you are trying to achieve is to insert a line after the first few lines of of a textfile.
head -n10 file.txt >> newfile.txt
echo "your line >> newfile.txt
tail -n +10 file.txt >> newfile.txt
If you don't want to rest of the lines from the file, just skip the tail part.
Solution 3 - Linux
First few lines: man head.
Append lines: use the >> operator (?) in Bash:
echo 'This goes at the end of the file' >> file
Solution 4 - Linux
sed -n '1,10p' filename > newfile
echo 'This goes at the end of the file' >> newfile