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Subject: BUG #19502: unix_socket_group doesn't work anymore
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: pierre.juhen@orange.fr
Reply-To: pierre.juhen@orange.fr, pgsql-bugs@lists.postgresql.org
Date: Sun, 31 May 2026 14:41:15 +0000
Message-ID: <19502-7f29e169bb2eda2c@postgresql.org>
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 <https://www.postgresql.org/message-id/19502-7f29e169bb2eda2c%40postgresql.org>
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The following bug has been logged on the website:

Bug reference:      19502
Logged by:          Pierre Juhen
Email address:      pierre.juhen@orange.fr
PostgreSQL version: 16.3
Operating system:   Linux
Description:       =20

Hi,

I developped an application on Alma Linux 9 and PostgreSQL 13.

I want to maintain it up to date, and try to "port" it to Alma Linux 10 and
PostgreSQL 16.13

Previously the appplication run under the identity of a plain user. The Unix
socket (/var/run/postgresql/.s.PGSQL.5432)  was owned by   postgres and the
group was that plain user one.

Now, postgreSQL refuses to launch with the following error :

2026-05-30 23:59:27.178 CEST [5163] LOG:  n'a pas pu initialiser le groupe
du fichier =C2=AB /var/run/postgresql/.s.PGSQL.5432 =C2=BB : Op=C3=A9ration=
 non permise
2026-05-30 23:59:27.178 CEST [5163] ATTENTION:  n'a pas pu cr=C3=A9er la so=
cket
de domaine Unix dans le r=C3=A9pertoire =C2=AB /var/run/postgresql =C2=BB
2026-05-30 23:59:27.180 CEST [5163] LOG:  n'a pas pu initialiser le groupe
du fichier =C2=AB /tmp/.s.PGSQL.5432 =C2=BB : Op=C3=A9ration non permise
2026-05-30 23:59:27.180 CEST [5163] ATTENTION:  n'a pas pu cr=C3=A9er la so=
cket
de domaine Unix dans le r=C3=A9pertoire =C2=AB /tmp =C2=BB
2026-05-30 23:59:27.180 CEST [5163] FATAL:  n'a pas pu cr=C3=A9er les socke=
ts de
domaine Unix

Translated by google in english :

2026-05-30 23:59:27.178 CEST [5163] LOG: Could not initialize the group for
the file '/var/run/postgresql/.s.PGSQL.5432': Operation not permitted
2026-05-30 23:59:27.178 CEST [5163] WARNING: Could not create the Unix
domain socket in the directory '/var/run/postgresql'
2026-05-30 23:59:27.180 CEST [5163] LOG: Could not initialize the group for
the file '/tmp/.s.PGSQL.5432': Operation not permitted
2026-05-30 23:59:27.180 CEST [5163] WARNING: Could not create the socket
Unix domain in the "/tmp" directory
2026-05-30 23:59:27.180 CEST [5163] FATAL: Could not create Unix domain
sockets

If I comment unix_socket_group in postgresql.conf, the system starts without
any problem.

The postgres heading process has got the right chown capability (cap_chown)

I don't undestand what append.

The same problem occurs with my development machine (Fedora 44 and and
PostgreSQL 18.3).

Recent changes in the kernel ?

Any help would be welcome.

Thanks,

Pierre