Closing open file without killing the process
Solution 1:
use lsof -p $PID and find the file descriptor (4th column)
root@blah:~# lsof -p 1737 | grep "(deleted)"
apache2 1737 root 6w REG 0,25 0 207401 (deleted)/var/log/apache2/other_vhosts_access.log
4th column is 6w, meaning file descriptor 6 and it was opened for writing (w).
Then:
gdb -p $PID
p close($FD)
eg:
gdb -p 1737
.....
(gdb) p close(6)
$1 = 0
...
Quit anyway? (y or n) y
Detaching from program: /usr/lib/apache2/mpm-prefork/apache2, process 1737
Solution 2:
Use the following command to find the deleted files file descriptors and you may truncate them afterwards
find /proc/ -mindepth 3 -maxdepth 3 \ -regex '/proc/[1-9][0-9]/fd/[1-9][0-9]' -type l -lname '*(deleted)' \ -printf '%p\n %l\n' 2>/dev/null