Less is broken in Linux

[giddie]

The -X option breaks mouse wheel scrolling for me in ArchLinux. It doesn't look like it does anything particularly useful; maybe BSD less is different?

-X or --no-init
       Disables sending the termcap initialization and deinitialization strings to the ter‐
       minal.   This  is  sometimes desirable if the deinitialization string does something
       unnecessary, like clearing the screen.

[sorin-ionescu]

I remember what that does. This is not a bug; it's a preference.

It prevents less from using the alternate screen and clearing the buffer when it exists. This allows you to write a command while referring to the man page, which is still partially on screen while less has exited.

I will not merge this.

[giddie]

Fair enough. On balance, though, I would not have thought this was the expected behaviour. I do hope you're rejecting this because you believe most people want this behaviour, and not because this is the behaviour you want. If your fork becomes OMZ 2, it'll have to cater to the majority out of the box. Just my opinion; take it or leave it. I really appreciate all the work you've put into this already.

[ColinHebert]

An overridden (and commented) version of $LESS without -X could be added to the zshrc template with a comment above to explain the issue.

This way, mac users will just ignore it, and linux users will be able to fix the -X issue easily.

[sorin-ionescu]

It's not Mac vs Linux. I have read a lot of blog posts and dot files when I wrote those less options. Some prefer -X; others, do not. There is benefit to -X because you do not need two terminal windows open (one for the man page and another for your command). You can just quit less, and the relevant portion of the man page is in front of you because it does not clear the screen. Execute the command and move on. I'll try to fit in a comment.

[giddie]

OK, I respect your opinion Sorin. If you think more people will want less to have -X, that's fine. To me, the behaviour felt broken, because I rely heavily on mouse scrolling in less (h and j are too slow, and I don't like the context jumps that result from Page Up / Page Down).

I do think another zstyle option in the .zshrc might be in order, though.

[ColinHebert]

What I meant to say isn't the mac/linux thing, I just presented it that way because the title of the issue is "Less broken in Linux" (I shouldn't have said it like that), it was more "A comment explaining to the users how the default -X could create a strange behaviour and how could it be fixed easily".

[sorin-ionescu]

I disagree on the zstyle. Less has too many switches.

[giddie]

Hmm; yes less has plenty of switches, but I see this as a serious issue that at least deserves a configuration option for two reasons:

1. You say that your rationale for setting -X by default is that you want to be able to see part of the manpage when you return to the prompt. Well, I have the opposite problem. I often enter a manpage to check something quickly, and want to see the output from previous commands when I return. This is clearly a matter of preference, and so on these grounds there is no strong argument for -X or against it.

2. There's a "principle of least surprise" issue here. As far as the average user is concerned, less, man, and other paging commands act like a special scrolling buffer. They can go up and down. In every other situation where you can go up and down (including outside a pager), the scrollwheel does the expected thing. However, when -X is added, scrolling up breaks the "special buffer" metaphor pretty badly: the bottom status disappears as it scrolls away, and what you see scrolling in at the top can be pretty weird, depending on what you were doing before you reached for the mouse. It is not immediately obvious that this is cause by a switch passed to less; my first thought was some terminal initialisation bug or oversight in terminal.zsh.

On the other hand, if -X is not there, the least surprising thing happens: your mouse scrolls the buffer. Maybe it's not the desired behaviour (we can assume this will be true for half the power-users). Those users that want the -X behaviour will almost certainly know how to enable it, or will have no trouble looking it up.

If you're dead-set of having -X set by default, I really think there must be a configuration option, so that it's immediately obvious to everyone doing even a cursory examination of their new setup that this is an issue.