Any idea how to resolve this issue?

`:~/pve-iso-2-pxe$ bash -x pve-iso-2-pxe.sh ../proxmox_ve_7.0.iso

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Create PXE bootable Proxmox image including ISO

Author: mrballcb @ Proxmox Forum (06-12-2012)

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'[' '!' 1 -eq 1 ']' +++ readlink -f ../proxmox_ve_7.0.iso ++ dirname /home/gravyflex/proxmox_ve_7.0.iso
BASEDIR=/home/gravyflex
pushd /home/gravyflex
'[' -L proxmox.iso ']'
rm proxmox.iso
for ISO in '*.iso'
'[' proxmox_ve_7.0.iso = '*.iso' ']'
'[' proxmox_ve_7.0.iso = proxmox.iso ']'
echo 'Using proxmox_ve_7.0.iso...' Using proxmox_ve_7.0.iso...
ln -s proxmox_ve_7.0.iso proxmox.iso
'[' '!' -f proxmox.iso ']'
'[' -d pxeboot ']'
pushd pxeboot
echo 'extracting kernel...' extracting kernel...
isoinfo -i ../proxmox.iso -R -x /boot/linux26
echo 'extracting initrd...' extracting initrd...
isoinfo -i ../proxmox.iso -R -x /boot/initrd.img ++ file --mime-type --brief /tmp/initrd.img
mimetype=application/octet-stream
case "${mimetype##*/}" in
echo 'unable to detect initrd compression method, exiting' unable to detect initrd compression method, exiting
exit 1`

lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 16.04.7 LTS Release: 16.04 Codename: xenial

file --mime-type --brief /tmp/initrd.img application/octet-stream