how to redirect the '&' command's log?

Question

here is the command:

 # ls >log 2>&1 &
 [1] 24274

now I want this line [1] 24274 to redirect a another file. any ideas?

Answer 1

Unless you're trying to get the job number, the easiest way to do this is to use $!, which will give you the PID of the most recent background job. For example:

$ sleep 30 & bg_pid=$!; echo $bg_pid
[2] 10100
10100

If you really want to get the job number back from the stored PID, perhaps to use Bash's job control instead of sending signals to the process with kill, you can do this:

jobs -l | fgrep $! | perl -ne 'print "$1\n" if /\[(\d+)\]/'

Answer 2

Use $!:

ls >log 2>&1 &
echo ls: pid=$!