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#1 2021-10-13 15:56:56

zpg443
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Registered: 2016-12-03
Posts: 227

[SOLVED] Blacklisting non-system-related packages (paccache)?

Short of manually (or by script) removing individual packages from the pacman cache, I do not see a way to blacklist specific packages from the pacman cache using paccache. Am I the only one who does not see a good reason to store backup copies for programs not essential to basic system operation?

Has adding such a feature ever been considered for paccache?

Last edited by zpg443 (2021-10-14 03:11:18)

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#2 2021-10-13 15:59:14

Trilby
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Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

It should be trivially easy to maintain your own list of packages either to keep or to purge (see paccache's '-i' flag).  But I don't see how this could be automatically built in aside from just inheriting someone else's lists.  There is no objective metric for what is "essential" - that's vague / subjective.  In order for a process to be automated it first needs to be defined.

Last edited by Trilby (2021-10-13 16:00:11)


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#3 2021-10-13 16:28:59

zpg443
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Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

As I understand it, paccache's i flag allows you to retain cache copies (by ignoring their removal). The existing mechanism for purging is to remove all of the cache, except for core-related programs identified with the i flag. As you stated, it is difficult to determine what is "essential".

It is for this practical reason (the need to exclude a handful of large packages, such as libreoffice, clearly not required to run Arch) that it would be better for paccache to have a flag to explicitly skip for retention to the cache, specified packages as comma separated values.

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#4 2021-10-13 17:22:24

Trilby
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Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

If you're proposing an option for the inverse behavior of the '-i' flag, that sounds reasonable and is well defined enough to potentially go to the bug tracker as a feature request (nevermind: see edit 2)

But scripting this is pretty trivial:

rm $(pacman -Sp $package-list | sed -n 's|file://||p')

EDIT: I suppose this only removes the current version from the cache - but if you do this regularly that'd be all that was there.  And if you are using paccache to remove old packages, it'd eventually remove any stragglers anyways.

EDIT 2: wait, what you want is the default behavior: if you have the list of packages you don't want in the cache, just specify them: no new flags needed:

paccache -rk0 $package-list

Last edited by Trilby (2021-10-13 17:41:56)


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#5 2021-10-13 23:33:38

zpg443
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Registered: 2016-12-03
Posts: 227

Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

Since I kept a record of basic installation packages, I decided to go with the basic '-i' approach for simplicity, and did these steps:

Remove all packages in the cache:

# paccache -rk0

Re-download without reinstalling using a custom list of 'basic install packages' (one package name per line):

# pacman -Sw $(cat ~/cache_include_list | cut -d' ' -f1)

Following each system upgrade, use paccache with the '-i' flag to ignore the removal of all packages in the list, but remove all other cache files:

 # paccache -rk0 -i - < ~/cache_include_list

Revised after feedback from Trilby (#6).

Last edited by zpg443 (2021-10-14 03:10:58)

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#6 2021-10-13 23:56:38

Trilby
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Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

Only one of those three attempts actually follows the syntax for the -i flag, but none of them do for the other flags which is the actual cause of the error that has nothing to do with the attempted use of the -i flag as you'd get the same error.  What you should use is:

paccache -rk0 -i - < ~/cache_include_list

But why are you using the -i flag now, I thought your goal was for the opposite (i.e., default) behavior listing packages to remove.

Last edited by Trilby (2021-10-13 23:58:00)


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#7 2021-10-14 03:08:37

zpg443
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Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

I do not want to, but I am using the '-i' flag because there is not currently a reverse flag.

Until then, go with the basic '-i' approach although I am not sure I have a good answer on which packages to retain if downgrading is needed.

Thanks for pointing out the missing '-' on rk0. I will revise post #5 to reflect the corrected syntax.

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#8 2021-10-14 03:53:58

Trilby
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Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

There is no reverse flag as that behavior is the default as noted in post #4.


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#9 2021-10-14 04:48:00

zpg443
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Registered: 2016-12-03
Posts: 227

Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

Trilby wrote:

There is no reverse flag as that behavior is the default as noted in post #4.

Will check that again for user error on my part. It did not work when I tried it before.

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#10 2021-10-14 17:30:48

zpg443
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Registered: 2016-12-03
Posts: 227

Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

Checked it again and found it still did not work. First, I created a file (test_cache) with two random packages, each on a new line:

kbreakout
kpat

After checking the pacman cache dir (/var/cache/pacman/pkg/) to ensure both packages were there, placed the test file in the home directory, then:

# paccache -rk0 $~/test_cache

The result was:

==> no candidate packages found for pruning

It will work with each package name on the command line with a space between:

# paccache -rk0 kbreakout kpat
==> finished: 2 packages removed (disk space saved: 6.2 MiB)

Last edited by zpg443 (2021-10-14 17:53:29)

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#11 2021-10-14 19:28:37

Trilby
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Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

zpg443 wrote:

It will work with each package name on the command line with a space between:

Yes, because that's how the command takes arguments.  Your other attempt is pretty nonsensical - I'd suggest you spend a bit of time learning how command shells (aka bash) work.  I really like the first two tutorials here.  Frankly I find it quite odd that you could be using arch linux for 5 years and apparently not know the basics of how the shell processes command line arguments - your time with arch will be much better if you study up on this.

In this case, if you'd like to have packages to purge saved one-per-line in a file, you can use the following command:

paccache -rk0 $(cat /path/to/package_list)

If you are using bash, you can use the following bashism which is slightly simpler:

paccache -rk0 $(< /path/to/package_list)

Last edited by Trilby (2021-10-14 19:31:07)


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#12 2021-10-14 20:17:19

zpg443
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Registered: 2016-12-03
Posts: 227

Re: [SOLVED] Blacklisting non-system-related packages (paccache)?

Thanks for the tutorials. I am comfortable with bash scripting, but not so much with sed, grep, redirecting and piping. And, it is not something I do every day.

Last edited by zpg443 (2021-10-14 20:18:21)

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