[bug#47163] [PATCH] doc: Add snippet for running 'guix refresh' on installed packages

[Xinglu Chen <public@yoctocell.xyz>]

On Tue, Mar 16 2021, Ludovic Courtès wrote:

>> * doc/guix.texi (Invoking guix refresh): Add snippet that runs 'guix refresh'
>> on all the packages installed in the current profile.
>
> [...]
>
>> +You can also quickly update all the packages installed in the current
>> +profile with the following snippet:
>> +
>> +@example
>> +$ guix refresh -u $(guix package --list-installed | cut -f1)
>> +@end example
>> +
>> +This is handy if you don't use manifests for installing packages into
>> +your profile.
>
> Note that if you type this literally, it fails along these lines:
>
> --8<---------------cut here---------------start------------->8---
> $ guix refresh -u grep
>
> Starting download of /tmp/guix-file.yLXS45
> From https://ftpmirror.gnu.org/gnu/grep/grep-3.6.tar.xz...
> following redirection to `https://gnu.mirror.constant.com/grep/grep-3.6.tar.xz'...
>  …6.tar.xz  1.5MiB                    2.3MiB/s 00:01 [##################] 100.0%
>
> Starting download of /tmp/guix-file.NgvvW4
> From https://ftpmirror.gnu.org/gnu/grep/grep-3.6.tar.xz.sig...
> following redirection to `https://mirrors.ocf.berkeley.edu/gnu/grep/grep-3.6.tar.xz.sig'...
>  …tar.xz.sig  833B                    1.8MiB/s 00:00 [##################] 100.0%
> gpgv: Signature made Mon 09 Nov 2020 05:40:03 AM CET
> gpgv:                using RSA key 155D3FC500C834486D1EEA677FD9FCCB000BEEEE
> gpgv: Good signature from "Jim Meyering <jim@meyering.net>"
> gpgv:                 aka "Jim Meyering <meyering@fb.com>"
> gpgv:                 aka "Jim Meyering <meyering@gnu.org>"
> gnu/packages/base.scm:99:12: grep: updating from version 3.4 to version 3.6...
> guix refresh: error: mkstemp!: Read-only file system
> --8<---------------cut here---------------end--------------->8---
>
> So I think this example may be misleading.  We could instead suggest
> ./pre-inst-env, with a link to “Running Guix Before It Is Installed”,
> and possibly mention the ‘--with-latest’ option as well.
>
> WDYT?

Sorry, I should have tested the command...  When you say "--with-latest",
do you mean `guix package -i grep --with-latest`?