POSIX 7 http://pubs.opengroup.org/onlinepubs/9699919799/utilities/expand.html
Expand tabs to spaces:
printf -e 'a\tb' | expand
The cool thing about this command is that it works well for inner tabs, e.g.:
printf '1\t1\n12\t1\n12345678\n'
Looks like:
1 1
12 1
12345678
After expand, it will still look the same: the first tab is expanded to 7 spaces, but the second one to only 6.
So you can easily take outputs with tabs, and replace them with spaces in a way that it looks exactly the same before pasting it somewhere else where you don't tabs to appear, e.g. Markdown.
The contrary. TODO