/usr/lib/petscdir/3.4.2/conf/petscvariables is in libpetsc3.4.2-dev 3.4.2.dfsg1-8.1+b1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | PETSC_ARCH=linux-gnu-c-opt
PETSC_DIR=/usr/lib/petscdir/3.4.2
include /usr/lib/petscdir/3.4.2/linux-gnu-c-opt/conf/petscvariables
|