dphys-swapfile | 3 2 + 1 - 0 !
1 file changed, 2 insertions(+), 1 deletion(-)

 first call chmod, then mkswap
 Avoids mkswap warning about insecure permissions, suggesting the
 permissions the file will be set to anyways afterwards.

dphys-swapfile | 17 17 + 0 - 0 !
dphys-swapfile.8 | 7 7 + 0 - 0 !
2 files changed, 24 insertions(+)

 check available disk space first to avoid filling up disks

dphys-swapfile.8 | 4 2 + 2 - 0 !
1 file changed, 2 insertions(+), 2 deletions(-)

 change /var/run/ example to /var/tmp/
 Using /var/run/ for swap files doesn't make sense anymore as /run/
 (to which /var/run/ symlinks nowadays) is usually a tmpfs.

dphys-swapfile | 8 4 + 4 - 0 !
1 file changed, 4 insertions(+), 4 deletions(-)

 replace "p q" by "p" since newer dc releases consider this syntax to be an error
Bug-Debian: https://bugs.debian.org/906767
Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/dphys-swapfile/+bug/1788681

dphys-swapfile | 10 10 + 0 - 0 !
1 file changed, 10 insertions(+)

 disable swapfile's cow for cow filesystems
 Touch swapfile before trying to set the CoW attribute.