Re: Bug#952927: [live-build] inconsistency and unnecessary complexity in bin checking
On Thu, 2020-03-12 at 11:11 +0900, John Crawley wrote:
> On 2020-03-02 07:12, jnqnfe@gmail.com wrote:
> > Package: live-build
> > Version: 1:20191221
> > Owner: jnqnfe@gmail.com
> > Severity: minor
> >
> > there are lots of checks being done that tools are available and
> > executable. this is done with a mixture of use of `which` and fixed
> > paths, redirection of output to /dev/null (`2>/dev/null`) and
> > redundant
> > executability tetsing on top of `which` checks (which already does
> > such
> > a check).
> >
> > this can be tidied up and robustified.
> > - we can move everything to `which` and drop fixed paths, thus
> > robustifying things should a bin every move (you never know).
> > - we can drop performing pointless `-x` testig on top of `which`
> > use,
> > since `which` already performs this and signals such in its exist
> > code
> > (returns 1 if nonexistant or nonexecutable).
> > - we can drop the `2>/dev/null` redirection which in my testing
> > seemed
> > to make no difference.
> >
> > proposal: switch to conditionals of the form:
> > ```
> > if [ $(which dpkg) ]; then
> > #whatever
> > fi
> > ```
>
> The use of 'which' is not universally regarded as robust: depending
> on
> the environment it can return true even if the executable does not
> exist, and may also output an error message, breaking the above test.
oh really. that's disappointing :/
> POSIX has 'command -v <command>' which should work under the
> #!/bin/sh
> shebang that live-build scripts use:
> if command -v dpkg >/dev/null
> then
> echo "we have dpkg"
> fi
>
> See: https://mywiki.wooledge.org/BashFAQ/081
yeah I actually came across the `command -v` solution a few days ago
but with the `which` based solution already in place saw little value
in reworking it. if `which` is flakey though, then perhaps its
important that we do change.
i've got rather a lot of stuff still to work on on live-build already
never mind anything else. would you have time to submit a patch
yourself?
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