How to set default tabs only for cat

catcommand linetabulation

I prefer to set tabs 4 however this may have some side effects, such as for example ls out put may look not properly aligned. How might I configure the terminal / cat to use four spaces for tabs for cat only?

Should I just alias / wrap cat to something that sets tabs 4, runs /bin/cat, then sets it back? My thinking is that this route is less preferable since in fact I would like this behaviour for less, diff, and other utilities.

Best Answer

The curses program tabs will allow you to change what the terminal believes to be the width of a ^I. This would make a simple script

tabs -4
cat "$@"
tabs -8

However, the processing of tab characters on terminals is notoriously wonky and I'm of the impression that you should never mess with them. I suggest using expand as in:

expand -4 "$@"

which is actually closer to what you intend.

added in reply to comment:

Far too many scripts count on cat meaning /bin/cat which explicitly does not change tabs. I'm not sure if you mean to replace or supersede /bin/cat, but you shouldn't. Better would be:

alias tcat='expand -4'

or

function tcat() {
    expand -4 "$@"
}

or similar.

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