Provavelmente, o arquivo tem o sinalizador imutável definido em seus atributos estendidos:
[email protected] ~/tmp % touch immutable
[email protected] ~/tmp % sudo chown root:root immutable
[sudo] password for user:
[email protected] ~/tmp % sudo chattr +i immutable
[email protected] ~/tmp % lsattr immutable
----i--------e-- immutable
[email protected] ~/tmp % sudo chown user:user immutable
chown: changing ownership of 'immutable': Operation not permitted
Para corrigir isso, basta executar sudo chattr -i file
:
[email protected] ~/tmp % sudo chattr -i immutable
[email protected] ~/tmp % lsattr immutable
-------------e-- immutable
[email protected] ~/tmp % sudo chown user:user immutable
[email protected] ~/tmp %