How to turn off word-wrap in less

Note: For the key binding, see the second part.

In less, it's called line folding rather than line wrapping.  To set it not to fold, use the -S option:

-S, --chop-long-lines

Causes lines longer than the screen width to be chopped rather than folded. That is, the portion of a long line that does not fit in the screen width is not shown. The default is to fold long lines; that is, display the remainder on the next line.

— less(1)

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Alternatively, as mentioned in the below comment, if you already opened the file, you can toggle the mode by typing -S (and then Enter for some implementations).

After disabling line folding, you can scroll sideways with the arrow keys.

If you want to stop wrapping permanently, cast these spells:

echo "#env" >> ~/.lesskey
echo "LESS = -S" >> ~/.lesskey
lesskey

Don't know if less has a option for that, but I use the most command which does that by default (and allows scrolling left/right to view it)