/var/lib/dpkg/alternatives

$ cat awk
auto
/usr/bin/awk
awk.1.gz
/usr/share/man/man1/awk.1.gz
nawk
/usr/bin/nawk
nawk.1.gz
/usr/share/man/man1/nawk.1.gz

/usr/bin/gawk
10
/usr/share/man/man1/gawk.1.gz
/usr/bin/gawk
/usr/share/man/man1/gawk.1.gz
/usr/bin/mawk
5
/usr/share/man/man1/mawk.1.gz
/usr/bin/mawk
/usr/share/man/man1/mawk.1.gz

$ update-alternatives --display awk
awk - auto mode
  link best version is /usr/bin/gawk
  link currently points to /usr/bin/gawk
  link awk is /usr/bin/awk
  slave awk.1.gz is /usr/share/man/man1/awk.1.gz
  slave nawk is /usr/bin/nawk
  slave nawk.1.gz is /usr/share/man/man1/nawk.1.gz
/usr/bin/gawk - priority 10
  slave awk.1.gz: /usr/share/man/man1/gawk.1.gz
  slave nawk: /usr/bin/gawk
  slave nawk.1.gz: /usr/share/man/man1/gawk.1.gz
/usr/bin/mawk - priority 5
  slave awk.1.gz: /usr/share/man/man1/mawk.1.gz
  slave nawk: /usr/bin/mawk
  slave nawk.1.gz: /usr/share/man/man1/mawk.1.gz