fix(debug xtrace): failures with mksh and with rd.live.debug

[FGrose]

Drop debug_on() debug_off() project-wide as setting xtrace is only
local in mksh. Use set -x directly instead. And use the shell's
local - feature to automate the restoration of local xtrace
option changes on function returns.

This fixes the bug with rd.live.debug where the debug_on() call
in the first getarg() call would fail to restore xtracing because
RD_DEBUG was not set. This also allows rd.live.debug to be
independent of rd.debug and eliminates 18 debug_off/debug_on calls.

This feature is present in bash and dash and not needed in mksh.
In mksh, local - (- alone) is an alias for typeset -p (synonymous
with declare -p in bash). Use local - with additional arguments to
avoid this alternate behavior in mksh.

This code works with dash since v0.5.2 (2005-09-26) and with bash
since v4.4 (2016-09-15).

Replace the nulling of debug_on()/debug_off() functions in
TEST-98-GETARG by overriding set +x in a temporary working copy of
the relevant code to aid in debugging a getarg() failure.

Checklist

• [✔] I have tested it locally.
• [✔] I have provided new testing code to replace the dropped functions.

[LaszloGombos]

What happens when /bin/sh points to mksh ?

[stale]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.

[FGrose]

@LaszloGombos > What happens when /bin/sh points to mksh ?

Independent of this code, with, ln -sf mksh /bin/sh, if module mksh is not requested, resolve_deps() will test the wrong file for script installs with a shebang, #!/bin/sh or #!/usr/bin/sh.

Pull Request #2359 addresses this bug.

[FGrose]

@LaszloGombos > What happens when /bin/sh points to mksh ? -- bug 2

Independent of this code, when these conditions apply,

1. host has ln -sf mksh /bin/sh, and
2. if a shell program is NOT specified, and
3. if NO modules are called with a dependency for the 99base module (where bash would be specified), then

resolve_deps() will install mksh, as the source for /bin/sh as in Script installs with a shebang.

Pull Request #2362 addresses this bug.

[stale]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.

[stale]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.