How to append the content of a file to a filename?

Question

I'm trying to achieve something like below.

I have a file called file_number and another file called serial_number which is containing a number inside it. Let's say 1.

Now, I want to append this number 1 from the serial_number file to the name of the my existing file called file_number. So, i want it to become file_number_1

How to do this in Unix??

Answer 1

I think you're asking to do this:

mv "file_number" "file_number_$(cat serial_number)"

Example demonstration:

neech@nicolaw.uk:~ $ touch file_number
neech@nicolaw.uk:~ $ echo 1 > serial_number
neech@nicolaw.uk:~ $ cat serial_number
1
neech@nicolaw.uk:~ $ ls -l
total 8
-rw-r--r--  1 nicolaw  staff  0 25 Oct 14:07 file_number
-rw-r--r--  1 nicolaw  staff  2 25 Oct 14:07 serial_number
neech@nicolaw.uk:~ $ mv "file_number" "file_number_$(< serial_number)"
neech@nicolaw.uk:~ $ ls -l
total 8
-rw-r--r--  1 nicolaw  staff  0 25 Oct 14:07 file_number_1
-rw-r--r--  1 nicolaw  staff  2 25 Oct 14:07 serial_number
neech@nicolaw.uk:~ $