uses renameat2(2) to swap content
command line interface to atomically swap content of two files.
When dual-booting between Linux and a Windows partitions I sometimes experience
drives not wanting to mount according to /etc/fstab. This tends to happen when
mounting a ntfs drive that is mounted both when booting from Windows partition
and by Linux partition. This leads me to edit /etc/fstab removing the drives
that fail to mount such that I can deal with that issue later. This leads to me
maintaining two variants of /etc/fstab. One is the ideal where every drive is
mounted and the other is the safe variant where only the non-ntfs drives are
mounted.
Now every time I want to switch between these two variants I have to at least
three commands (of a combination of mv and cp or just three mv).
rex is for this use-case. It swaps file variants atomically.
# switch
rex /etc/fstab /etc/ftstab.variant
# switch back
rex /etc/fstab /etc/ftstab.variantcd config
cp important.config important.config.prev
# work on the alternative config
vim important.config
# test important program
# we tested and are now ready to use the previous config again
# and we save the edited important.config for later
cp important.config important.config.new
mv important.config.prev important.config
rm important.config.prev
# It is now later and we want to continue working on important.config.new
cp important.config important.config.prev
mv important.config.new important.config
rm important.config.new
# work on the alternative config
vim important.config
# this is the workflowcd config
cp important.config important.config.variant
# Start work on the new variant
vim important.config
# test important program
# we tested and are now ready to use the original variant again
# and we would like to save the edited important.config variant for later
rex important.config important.config.variant
# It is now later and we want to continue working on important.config.new
rex important.config important.config.variant
vim important.config
# this is the workflow