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Question1 answer· Accepted3,930 followingPosted 31 Aug 2026, 17:55 UTC35.3K views1,142 votes

psql: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: FATAL: Peer authentication failed for user "postgres" (Ubuntu)

When I try to open psql with this command: psql -U postgres I get this error: psql: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: FATAL: Peer authentication failed for user "postgres" But it connects successfully when I use: sudo -u postgres psql Can someone please explain what is happening and how to diagnose/fix this pro

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Question1 answer· Accepted3 comments1,225 followingPosted 09 Aug 2026, 16:02 UTC95.2K views1,519 votes

error "/lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.33' not found"

Here is My Dockerfile: FROM ubuntu:20.04 RUN apt-get update && apt-get upgrade -y RUN apt-get install libssl-dev RUN apt-get install -y -q build-essential curl RUN curl https://sh.rustup.rs -sSf | sh -s -- -y ENV PATH="/root/.cargo/bin:${PATH}" WORKDIR /command-agent COPY . /command-agent RUN cargo build --release COPY /command-agent/target/release/c

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Question1 answer· Accepted1 comment3,168 followingPosted 28 Jun 2026, 10:34 UTC63.5K views607 votes

Ubuntu 20.04 upgrade, Python missing libffi.so.6

I recently upgraded my OS to Ubuntu 20.04 LTS. Now when I try to import a library like Numpy in Python, I get the following error: ImportError: libffi.so.6: cannot open shared object file: No such file or directory I tried installing the libffi package, but apt can't locate it: sudo apt-get install libffi Reading package lists... Done Building dependency tre

Question1 answer· Accepted2 comments3,458 followingPosted 18 Mar 2026, 21:23 UTC101.7K views555 votes

networkmanager script failing, how to see full logs output

journalctl -u NetworkManager.service tells me dispatcher: 01-ifupdown [...] /etc/NetworkManager/dispatcher.d/01-ifupdown exited with error status 1 This is almost certainly a script we have hooked/symlinked in /etc/network/if-up.d/our-hook , however all such scripts run without error when run directly. Where can I find, or how can I enable, a full capture of

Question1 answer· Accepted3,639 followingPosted 01 Feb 2026, 10:46 UTC95.5K views2,279 votes

using docker-compose without sudo doesn't work

I was recently told that running docker or docker-compose with sudo is a big nono, and that I had to create/add my user to the docker group in order to run docker and docker-compose commands without sudo . Which I did, as per the documentation here Now, docker runs normally via my user. e.g. : ~$ docker run hello-world Unable to find image 'hello-world:lates

Question1 answer· Accepted3 comments763 followingPosted 15 Jan 2026, 16:54 UTC22.5K views3,165 votes

SSH Tunnel - Performant alternatives for exposing a local port to remote machines?

I have Server A running at home in a Carrier-Grade NAT environment. Due to this I cannot open a port directly in my router. I also have Server B on a cloud hosting provider, which has a static public IP address that can have ports opened to. Both machines run Ubuntu linux. So far the best solution for me was SSH Tunneling, but it comes with a performance dra

Question1 answer· Accepted3,546 followingPosted 10 Dec 2025, 09:14 UTC105.3K views2,105 votes

Running Docker on Google Colab

I'm trying to run Docker on Google Colab, and I'm having some trouble. I followed the steps to install Docker on Ubuntu ( https://docs.docker.com/engine/install/ubuntu/ ), which are very similar to the steps that others have used for installing it on Digital Ocean ( https://colab.research.google.com/drive/10OinT5ZNGtdLLQ9K399jlKgNgidxUbGP#scrollTo=9zp-VmLsws

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Question1 answer· Accepted4,586 followingPosted 09 Jun 2025, 04:33 UTC70.1K views2,065 votes

Dependency issue installing google-chrome-stable through Ubuntu docker

I have a Dockerfile that attempts to install the package google-chrome-stable among other packages in Ubuntu (v16 Xenial I think) as part of a Gitlab pipeline step. I have had no issues until recently, when the step started failing with this issue: Some packages could not be installed. This may mean that you have requested an impossible situation or if you a

Question1 answer· Accepted4,795 followingPosted 25 Apr 2025, 15:37 UTC128.2K views4,056 votes

ping returns IPV6 address on ubuntu 20.04

I have installed GitLab on a cloud VM and shortly after stood up a second VM as a postfix server with the same provider (Hetzner) I first noticed a problem when I went back to the GitLab server to enable SMTP Email and nothing was being sent, not even any logs on the mail server to say a connection was attempted. On the GitLab server I tried to ping the mail

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