Re: [PATCH v3] cpupower: Make help command available for custom install dir

[Shuah Khan]

On 7/2/24 12:52, Roman Storozhenko wrote:
> On Tue, Jul 2, 2024 at 9:40 AM Roman Storozhenko
> <romeusmeister@xxxxxxxxx> wrote:
> > On Mon, Jul 1, 2024 at 9:40 PM Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:
> > > On 6/29/24 04:48, Roman Storozhenko wrote:
> > > > On Fri, Jun 28, 2024 at 9:45 PM Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:
> > > > > On 6/28/24 05:30, Roman Storozhenko wrote:
> > > > > > On Thu, Jun 27, 2024 at 7:33 PM Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:
> > > > > > > On 6/27/24 01:49, Roman Storozhenko wrote:
> > > > > > > > When the 'cpupower' utility installed in the custom dir, it fails to
> > > > > > > > render appropriate help info for a particular subcommand:
> > > > > > > > $ LD_LIBRARY_PATH=lib64/ bin/cpupower help monitor
> > > > > > > > with error message like 'No manual entry for cpupower-monitor.1'
> > > > > > > > The issue is that under the hood it calls 'exec' function with
> > > > > > > > the following args: 'man cpupower-monitor.1'. In turn, 'man' search
> > > > > > > > path is defined in '/etc/manpath.config'. Of course it contains only
> > > > > > > > standard system man paths.
> > > > > > > > Make subcommands help available for a user by setting up 'MANPATH'
> > > > > > > > environment variable to the custom installation man pages dir. That
> > > > > > > > variable value will be prepended to the man pages standard search paths
> > > > > > > > as described in 'SEARCH PATH' section of MANPATH(5).
> > > > > > >
> > > > > > > What I am asking you is what happens when you set the MANPATH before
> > > > > > > running the command?
> > > > > >
> > > > > > It adds the custom search path to the beginning of the MANPATH variable.
> > > > > > I tested this case. All works as expected.
> > > > >
> > > > > Let's try again. What happens if you run the command with MANPATH set and
> > > > > exported and then run the command. Can you send the output?
> > > >
> > > > hedin@laptop:~/prj/cpupower/install/usr$ echo $MANPATH
> > > > /tmp/
> > > > hedin@laptop:~/prj/cpupower/install/usr$ LD_LIBRARY_PATH=lib64/
> > > > bin/cpupower help monitor
> > > > ...................
> > > > man output
> > > > ...................
> > > > hedin@laptop:~/prj/cpupower/install/usr$ echo $MANPATH
> > > > /tmp/
> > > > hedin@laptop:~/prj/cpupower/install/usr$
> > >
> > > Is this with your patch or mainline? Can you give cut and paste
> > > the man output here for the mainline coupower without your patch?
> >
> > The above output is from my patch.
> > This is the output from the mainline:
> > hedin@laptop:~/prj/cpupower/install/usr$ sudo LD_LIBRARY_PATH=lib64/
> > bin/cpupower help monitor
> > [sudo] password for hedin:
> > No manual entry for cpupower-monitor
> > hedin@laptop:~/prj/cpupower/install/usr$ echo $MANPATH
> > /tmp/
> > hedin@laptop:~/prj/cpupower/install/usr$
> Based on our today's conversation the following is the output for the mainline:
>
> hedin@laptop:~/prj/cpupower/install/usr$
> MANPATH="/home/hedin/prj/cpupower/install/usr/man:"
> LD_LIBRARY_PATH=lib64/ bin/cpupower help monitor
> hedin@laptop:~/prj/cpupower/install/usr$ echo $MANPATH
>
> .............
> man output
> .............
>
> hedin@laptop:~/prj/cpupower/install/usr$ export
> MANPATH="/home/hedin/prj/cpupower/install/usr/man:"
> hedin@laptop:~/prj/cpupower/install/usr$ echo $MANPATH
> /home/hedin/prj/cpupower/install/usr/man:
> hedin@laptop:~/prj/cpupower/install/usr$ LD_LIBRARY_PATH=lib64/
> bin/cpupower help monitor
>
> .............
> man output
> .............
>
> hedin@laptop:~/prj/cpupower/install/usr$ LD_LIBRARY_PATH=lib64/ sudo
> bin/cpupower help monitor
> [sudo] password for hedin:
> bin/cpupower: error while loading shared libraries: libcpupower.so.1:
> cannot open shared object file: No such file or directory
>
> As you can see we can use MANPATH for correct help invocation, unless
> we call it with 'sudo'. I can guess that it simply
> inherits the environment variables from the root shell that contains
> no 'MANPATH' variable set with an ordinary user.

sudo -s will inherit the environment. Check sudo man page.

> Worth mentioning this in an appropriate manpage?

I don't think so.

thanks,
-- Shuah