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root@cunix:/home/cunix# sudo apt-get remove fern-wifi-cracker
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libqt4-test libqt4-sql-mysql mysql-common libqt4-xmlpatterns libqt4-help
  python-qt4 python-sip libqt4-sql-sqlite libqt4-sql macchanger
  libqt4-designer libmysqlclient16 python-scapy libqt4-scripttools
Use 'apt-get autoremove' to remove them.
The following packages will be REMOVED:
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 3,514kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 167661 files and directories currently installed.)
Removing fern-wifi-cracker ...
dpkg (subprocess): unable to execute installed pre-removal script (/var/lib/dpkg/info/fern-wifi-cracker.prerm): Exec format error
dpkg: error processing fern-wifi-cracker (--remove):
 subprocess installed pre-removal script returned error exit status 2
Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)

how to uninstall?

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Try running:

echo -e '#!/bin/bash\nexit0' | sudo tee /var/lib/dpkg/info/fern-wifi-cracker.prerm

and then remove the package with:

sudo apt-get purge fern-wifi-cracker

The first command will replace the pre-uninstall script with a script that never fails.

share|improve this answer

Sounds like the program has a bad uninstall script. You might try purging it to see if that works. Otherwise it's gonna need some real elbow grease to get rid of.

sudo apt-get purge fern-wifi-cracker

Hope this helps.

PS: Also try Rebooting first to see of that loosens anything up.

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