Recover a deleted open file in linux

gistfile1.txt

This is simple to test. 

Step 1

Create a test file

$ echo "OMG Please dont delete me" > /tmp/myfile.text

Step 2

Do something to hold on to the open file (do not close the process obviously)

$ irb
irb(main):001:0> File.open('/tmp/myfile.text')
=> #<File:/tmp/myfile.text>

See the file being open with 'lsof'

$ lsof | grep myfile
irb       21505    veewee    3r      REG  253,0       26  417220 /tmp/myfile.text

Step 3

In another terminal

$ rm /tmp/myfile.txt

Verify the file is 'deleted'

$ lsof | grep myfile
irb       21505    veewee    3r      REG  253,0       26  417220 /tmp/myfile.text (deleted)

Step 4

Change to the /proc/<pid>/fd

$ cd /proc/21505/fd
$ ls -l 
total 0
lrwx------ 1 veewee veewee 64 Mar 21 23:44 0 -> /dev/pts/0
lrwx------ 1 veewee veewee 64 Mar 21 23:44 1 -> /dev/pts/0
lrwx------ 1 veewee veewee 64 Mar 21 23:44 2 -> /dev/pts/0
lr-x------ 1 veewee veewee 64 Mar 21 23:44 3 -> /tmp/myfile.text (deleted)

Now copy the deleted fd to another location 

$ cp 3 /tmp/myfile2.txt
$ cat /tmp/myfile2.text
OMG Please dont delete me

Not something you usually have to do, but could be a life saver.