E: Could not get lock /var/lib/apt/lists/lock. It is held by process 6435 (packagekitd) N: Be aware that removing the lock file is not a solution and may break your system. E: Unable to lock directory /var/lib/apt/lists/ code example

Example 1: apt lock

rm -rf /var/cache/apt/* /var/lib/dpkg/lock /var/lib/dpkg/lock-frontend \
/var/cache/debconf/ /var/lib/apt/lists/* \
/var/lib/dpkg/lock /var/lib/dpkg/lock-frontend /var/cache/debconf/

Example 2: E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?

$ sudo dpkg --configure -a
dpkg: error: parsing file '/var/lib/dpkg/updates/0004' near line 0:
newline in field name '#padding'