As dbarnett@ reported on #9, our default of `less`, combined with our
default of enabling color on TTYs, means that we print ANSI codes to
`less` by default. Unless the user has set e.g. `$LESS=R`, `less` is
going to escape those codes, resulting in garbage like this:
```
@ ESC[1;35mbb39c26a29feESC[0m ESC[1;33m(no email configured)ESC[0m ESC[1;36m2022-12-03....
```
I guess most of us didn't notice because we have something like
`$LESS=FRX` set.
This patch changes our default from `less` to `less -FRX`. Those are
the flags we're using for our internal hg distribution at Google, and
that has seemed quite uncontroversial.
I added a pointer from the changelog to the tracking issue while at
it.
It should be more reliable than parsing a command string into array.
Also updated some of the doc example to use array syntax. I don't think
"C:/Program Files" was parsed properly, but might work thanks to Windows
magic.
Teach Ui's writing functions to write to a pager without touching the
process's file descriptors. This is done by introducing UiOutput::Paged,
which spawns a pager that Ui's functions can write to.
The pager program can be chosen via `ui.pager`. (defaults to Defaults to
$PAGER, and 'less' if that is unset (falling back to 'less' also makes
the tests pass).
Currently, commands are paginated if:
- they have "long" output (as defined by jj developers)
- jj is invoked in a terminal
The next commit will allow pagination to be turned off via a CLI option.
More complex pagination toggling (e.g. showing a pager even if the
output doesn't look like a terminal, using a pager for shorter ouput) is
left for a future PR.
Unfortunately, TOML requires quotes around the argument. So, the
usage is `jj --config-toml ui.color=\"always\"` in bash. The plan is
to eventually have a `--config` option with simpler syntax for
simple cases.
As discussed in https://github.com/martinvonz/jj/discussions/688.
