PR #702

This addresses the changes requested by Rycieos at #702.
To summarize:
The flag -v exists since first version of sudo and we can't find a
reason why to use true.

This commit changes the default behaviour of sudo detection to use
sudo -v instead of executing true.

Validation of sudo credentials is done by invoking a command (true).
This means that, if the user has sudo credentials, a root session is
opened and then closed. Potentially generating two PAM messages plus the
sudo line for true being executed as root.

This commit adds an option to use the validate command (sudo -v) to test
for credentials.
Validate command DOES NOT open a session and does not log anything on
success.
It still logs "a password is required" in case of failure but those
lines are easier to filter out searching for COMMAND=validate.

I've opted for adding LP_USE_SUDO_VALIDATE instead of replacing the
default behaviour because I'm not sure if -v is on every system.
The default value is 0: using the old behaviour (execute true).

Mercurial is written in Python 2, so it was always slow. There is work
ongoing to rewrite it in Rust, but as the replacement is not at feature
pairity yet, they are shipping the binary as 'rhg'. Since some might
want to use different binaries for different things, give a config
option to pick which binary to use for prompt data gathering.

Resolves #701

Without these functions defined, each prompt invocation would force the
shell to check if the command was valid, and generate an error message
if it was not. We know that it won't be, so we can shortcut that by
setting it as such.

More importantly, if the Bash function command_not_found_handle() is
set, it will be executed for each function that is not set. For Git or
HG, this is only one. But for SVN, it is enough to lock the prompt for a
while.

Fixes #696

If no current context was set and the KUBE_NAMESPACE feature was
enabled, kubectl would print an error message, which would leak through
to the terminal.

Fixes #695

The documentation libraries were out of date.
Fix the Ubuntu version badge, since the version used is no longer
supported upstream, and therefore has no badge. 22.04 isn't actually
released yet, but already exists and has a badge, and will exist for a
long time as a LTS.
Fix a typo.

With the removal of the command -v check, anything returned on stdout
would make acpi be a valid backend. This can happen in the
command_not_found_handle() function is defined.

Also don't pick a backend if the data function returns an error code.

Further strictness could be to check that the string returned is a valid
int, but that is probably overkill.

Fixes #690

Zsh by default will error if a glob matches nothing (a smart default).
We need it to not error, and even better, to not use the Bash default of
using the pattern. Set nullglob to expand it to nothing.

Don't set the Bash version of nullglob in liquidprompt, since Bash
doesn't do local options well, and not at all until version 4.4. It is
safe to expand to a single string with the "*" in it, since the first
check we do is for the file existing, which it will not.

Add the sysfs power supply interface to the external-tool-tester.sh.

Add sysfs function, tests, and documentation.
Set sysfs method as default.
Remove LP_BATTERY_ID from __lp_battery_acpi() as unreliable.

Co-authored-by: Mark Vander Stel <mvndrstl@gmail.com>

Zinit has a new home; its old home was deleted.

Debian seems to not have images for stable anymore on repology.org. I am
not sure if this is a bug or not, but unstable has the latest packages
anyway, so switch to that.

When running in non-interactive environments sometimes the TERM is set to 'unknown' rather than being unset, e.g. https://askubuntu.com/questions/1091553/how-do-i-fix-error-opening-terminal-unknown-on-ubuntu-server

When ACPI returns multiple batteries, and not all of them related to laptop
battery, this option can be used to specify which battery to be used for
status information. Example of this is Logitech Unifying Receiver, returning
battery information for keyboard/mouse.

Github has removed this version of Ubuntu VM, as it is no longer
supported by the upstream.

Change the targets to the rolling versions of "latest", to prevent
needing to make these changes again. My original logic was to run on as
many OSs as possible, but in reality all of these versions act so
similar in terms of shell functionality that it is kinda pointless. One
VM of each OS should be fine.

Broken in commit 4c81ef40, if a
temperature was ever recorded above the threshold, _lp_temperature()
would always return that high value, never resetting.

Fixes #686

Even farther through the work for 2.1, the Changelog really needed
updating.

PR/672

Co-authored-by: Mark Vander Stel <mvndrstl@gmail.com>

[bash-preexec](https://github.com/rcaloras/bash-preexec) "provides
preexec and precmd hook functions for Bash in the style of Zsh".

Unfortunately, it interferes with `trap DEBUG` and `PROMPT_COMMAND`
behavior used by `LP_ENABLE_ERROR` and `LP_ENABLE_RUNTIME`.

Fortunately, since liquidprompt already supports add-zsh-hook behavior,
we can use those hooks as guides to where we should add hooks for
bash-preexec.

These hooks get set if __bp_imported is "defined"; this is set by
bash.

Note on tests/test_bash_preexec.sh: test functions' contents are wrapped
in  `( ... )` subshells so that the sourcing and installation of
bash-preexec is confined to that test and does not pollute others.

PR/681

Don't know why I didn't think of this before. While contexts can
contain any character, namespaces are limited to the normal DNS name
rules, and so we can parse on the last instance of a delimiting
character found.

Add data gathering for the configured default namespace of the current
kubectl context. Display that data as a string directly after the
context string, separated by a colon.

While this is a separate chunk of data from the context, it is actually
part of the context definition, and so it makes sense to display it
along with the context.

While most Kubernetes objects are subject to the strict DNS name
restrictions, kubectl contexts never have their name server-side, and so
do not have the same restrictions. This means a context name can include
any characters, meaning we have no safe way to parse it out of a data
string. I wanted to use:

line=$(kubectl config view --minify --output 'jsonpath={.current-context}{" "}{..namespace}')
IFS=' ' read kubernetes_context kubernetes_namespace <<<"$line"

But since spaces can be in a context name, this would break.

Hooks have always been a mess. There was no organization when they were
added, as when the project first started there was no need for them.

To make things consistent, break out disabling hooks into
__lp_disable_hooks(), and make prompt_on() be the enabler of hooks. Then
have lp_activate() disable hooks at the start, and enable hooks at the
end.

Some small changes around how state is detected, but no functional
difference here.

Based on the work done in ecdde384, the
prompt_bang and prompt_subst options, which handle '!' and '$'/'`'
characters respectively, can be left untouched. When running
__lp_escape(), those options are checked, and if set, their characters
are escaped.

prompt_percent however, must still be enabled always. The shell sequence
escapes, '%{' and '%}' only work when the option is enabled. Maybe
someday we can detect when the option is off and disable all terminal
formatting, but it doesn't seem worth the effort.

Backslashes must be escaped even on Zsh to prevent confusion with a
backslash directly preceding a character that would give is special
meaning.

For some reason, Bash ignores a '\$' sequence when the promptvars option
is off, printing it as '$'. It does not do the same for a backtick
escaped: '\`' is printed as '\`'. To prevent this issue, detect if the
option is on, and if so, escape both '$' and '`'.

Running 'shopt' is actually faster than either a [[ ]] or (( ))
expression.

PR/679

Extension to #496 to add [AWS Vault](https://github.com/99designs/aws-vault)
support. AWS Vault does not set the AWS_PROFILE/AWS_DEFAULT_PROFILE
variables, but does add AWS_VAULT. Since this is philosophically the
same as showing an AWS profile on the prompt, I simply added AWS_VAULT
to the detection chain.

PR/678

Also remove some trailing space.

Closes: nojhan/liquidprompt#675

This was missed in the PR for the Ruby Virtualenv section.
The order in the docs for Terraform and Kubecontext was backwards from
the order in the code.
Moved parts of the PS1 building to different lines to make it easier to
read and add new sections.

Resolves #676

PR/673

LP_KUBECONTEXT_DELIMITER_SUFFIX removes a suffix (dev-cluster and - becomes ->
dev). But sometimes the boilerplate part is a prefix, as when using AWS
EKS (Elastic Kubernetes Service).

`aws eks update-kubeconfig --name $CLUSTER_NAME` sets the cluster's ARN
as the context name, most of which is boilerplate:
`arn:aws:eks:$REGION:$ACCOUNT_ID:cluster/$CLUSTER_NAME`.

PR/671