I appear to miss understand the negated look ahead command. I'm trying to remove all lines that don't start with a certain pattern:

Validating that my regex matches:

[admin@kvm5a ~]# rbd showmapped | perl -pe 's/^\d+\s+.*\n//g'
id pool     image         snap device
[download]

When trying to use the negated look ahead (?!) it doesn't remove the header:

[admin@kvm5a ~]# rbd showmapped | perl -pe 's/^?!\d+\s+.*\n//g'
id pool     image         snap device
0  rbd_hdd  vm-209-disk-1 -    /dev/rbd0
1  rbd_hdd  vm-107-disk-1 -    /dev/rbd1
10 rbd_hdd  vm-144-disk-1 -    /dev/rbd10
11 rbd_hdd  vm-145-disk-1 -    /dev/rbd11
12 rbd_hdd  vm-151-disk-1 -    /dev/rbd12
13 rbd_hdd  vm-154-disk-1 -    /dev/rbd13
14 rbd_hdd  vm-170-disk-1 -    /dev/rbd14
15 rbd_hdd  vm-204-disk-1 -    /dev/rbd15
16 rbd_nvme vm-100-disk-1 -    /dev/rbd16
17 rbd_hdd  vm-171-disk-1 -    /dev/rbd17
18 rbd_hdd  vm-291-disk-1 -    /dev/rbd18
19 rbd_hdd  vm-285-disk-1 -    /dev/rbd19
2  rbd_nvme vm-101-disk-1 -    /dev/rbd2
20 rbd_nvme vm-212-disk-1 -    /dev/rbd20
21 rbd_nvme vm-211-disk-1 -    /dev/rbd21
22 rbd_nvme vm-212-disk-2 -    /dev/rbd22
23 rbd_nvme vm-211-disk-2 -    /dev/rbd23
24 rbd_nvme vm-212-disk-3 -    /dev/rbd24
25 rbd_nvme vm-211-disk-3 -    /dev/rbd25
26 rbd_hdd  vm-300-disk-1 -    /dev/rbd26
3  rbd_hdd  vm-108-disk-1 -    /dev/rbd3
4  rbd_hdd  vm-104-disk-1 -    /dev/rbd4
5  rbd_hdd  vm-109-disk-1 -    /dev/rbd5
6  rbd_hdd  vm-123-disk-1 -    /dev/rbd6
7  rbd_hdd  vm-138-disk-1 -    /dev/rbd7
8  rbd_hdd  vm-141-disk-1 -    /dev/rbd8
9  rbd_hdd  vm-143-disk-1 -    /dev/rbd9
[download]

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