$tool bits

Same procedure as last time? Same procedure, just for stuff which won’t require an own post (yet).

» curl

Save with remote filename (short -O):

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curl http://example.com --remote-name

Save with given filename (short -o):

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curl http://example.com --output filename

http://www.compciv.org/recipes/cli/downloading-with-curl/

To follow redirects add --location (short -L). Silent add --silent (short -s).

» dd

» Copy an ISO to an USB-stick

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sudo dd if=ubuntu-20.04.1-live-server-amd64.iso of=/dev/xyz bs=16M status=progress

https://www.cyberciti.biz/faq/creating-a-bootable-ubuntu-usb-stick-on-a-debian-linux/

» Takeover Installation

Overwrite your existing system. Sseems to be a bit buggy, maybe important parts of the image itself get overwritten. Preferably, store your image in a tmpfs mount (e.g. /run/shm).

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xz -d -c /rum/shm/talos.raw.xz | dd of=/dev/sda bs=16M status=progress && sync

» envsubst

Replace environment variables (e.g. ${MY_VAR}) in a file:

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envsubst < "source.txt" > "destination.txt"

If the input and output file should be the same:

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envsubst < "source.txt" | sponge "source.txt"

or without sponge but more verbose:

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envsubst < "source.txt" > "destination.txt" && mv "destination.txt" "source.txt" && rm "destination.txt"

envsubst is part of the gettext package and sponge of the moreutils package in Alpine Linux.

Reference: derobert and Derek Mahar

» find

List all files with a specific name, e.g. .DS_Store:

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find . -type f -name '.DS_Store'

Add -delete to delete all of them.

» git

» Delete remote tag

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git push --delete origin <TAG>

» Delete merged branches

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git fetch --prune
git branch -vv | grep ': gone]' | grep -v '\*' | awk '{ print $1; }' | xargs -r git branch -d

Reference: https://digitaldrummerj.me/git-remove-local-merged-branches/

» Globally set default branch to main

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git config --global init.defaultBranch main

» Rebase current branch to drop a given commit

Attention to the ~:

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git rebase -i <commit-hash-to-remove>~

Then “normally” drop the commits you want to remove.

Reference: David Deutsch and KiriSakow

As an alternative and you know that the commit you want to remove is within the last N (e.g. 10) commits, use:

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git rebase -i HEAD~10

» Compare local branch with remote branch

Gets the current branch name from a subshell, so you can reuse the command from your shell history.

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git diff origin/$(git rev-parse --abbrev-ref HEAD)

» Reset local branch to remote branch

Similarly to the comparison, we can reset our local branch to the remote branch:

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git reset origin/$(git rev-parse --abbrev-ref HEAD)

» Always rebase against default branch

Some repos use main, some still master as their default branch. When you use rebase from history with the default branch hardcoded, it will fail when it’s a different default branch. Use the subshell to figure out the default branch, so you can always use this command from your shell history.

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git rebase -i $(git symbolic-ref refs/remotes/origin/HEAD --short) --update-refs

» Github Workflows

» Access a private repository

When you need access to another private repository inside a Github Workflow (e.g. private Go package repo), add this to your Job’s steps:

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- name: "Setup git to fetch private repos"
  run: git config --global url.https://${{ secrets.ACCESS_TOKEN }}@github.com/.insteadOf https://github.com/

Where ACESS_TOKEN is a token which has access to the private repo.

References:

• https://stackoverflow.com/a/66094537/7125878
• https://maelvls.dev/gh-actions-with-tf-private-repo/

» grep

List all files with occurences of SearchPattern in /path/to/folder and subfolders:

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grep --color=always --recursive --binary-file=without-match --files-with-matches --ignore-case --fixed-strings "SearchPattern" /path/to/folder

If you want to use a regexp, remove --fixed-strings.

Reference: How to use “grep” command to find text including subdirectories

» helm

» Cascade check possible null values

When you want to check a value (here addr) where other sections might be null (e.g. networking or ipv4) use round brackets so the if condition will be false instead of just crashing.

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{{- if not ((.Values.networking).ipv4).addr }}
    {{ fail "setting 'networking.ipv4.addr' is required"}}
{{- end }}

» Resource Checksum Annotation

Add the checksum of another resource (e.g. configmap or secret) to the deployment annoatations. This way, the deployment will be restarted when the checksum (configmap/secret) changes. Otherwise, it could be easily forgotten to restart the deployment and you are wondering why it doesn’t behave as you would expect.

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annotations:
    checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}

Reference

» Homebrew

» Cleanup and upgrade everything

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brew autoremove; brew upgrade; brew upgrade --cask --greedy

» Bundle

Dump:

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brew bundle dump --global --all

Install:

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brew bundle --global --all

Cleanup:

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brew bundle cleanup --global --all

» Remove all installed tools

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brew remove --force $(brew list --formula)
brew remove --cask --force $(brew list)

https://apple.stackexchange.com/a/339096/487634

» KeePassXC

Export password as environment variable:

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KEY=$(keepassxc-cli show <database.kdbx> -k <keyfile.keyx> "<entry name>" -a Password)

» Minio Client

» Add Oracle Object Storage

• Create a “Customer Secret Key” in your user settings.
• The Region Name is shown in the Web-UI. Find the corresponding Region Identifier: https://docs.oracle.com/en-us/iaas/Content/General/Concepts/regions.htm
• Find your Object Storage Namespace (in the Web-UI shown on the Tenancy Details page): https://docs.oracle.com/en-us/iaas/Content/Object/Tasks/understandingnamespaces.htm

Adjust <NAMESPACE> and <REGION> and add the following entry to your Minio Client Config (e.g. ~/.mc/config.json):

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"oracle": {
    "url": "https://<NAMESPACE>.compat.objectstorage.<REGION>.oci.customer-oci.com",
    "accessKey": "CHANGE_ME",
    "secretKey": "CHANGE_ME",
    "api": "s3v4",
    "path": "auto"
}

https://docs.oracle.com/en-us/iaas/Content/Object/Concepts/dedicatedendpoints.htm

» NixOS

Use sudo as channels are set per user!

Show the current release channel:

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sudo nix-channel --list

Switch to another channel, e.g. 23.05:

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sudo nix-channel --add https://channels.nixos.org/nixos-23.05 nixos

Update the system (equivalent to apt update && apt upgrade on Debian):

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sudo nixos-rebuild switch --upgrade

Delete old generations:

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sudo nix-collect-garbage --delete-old --delete-older-than 14d

https://nixos.org/manual/nixos/stable/#sec-upgrading

» Prometheus

» 0 instead of no data

Add OR on() vector(0) to your query.

Credits: Nicolai Antiferov

» tar

extract:

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tar --extract --gzip --file file.tar.gz [file1 file2 dir1 dir2]

Add --verbose when you want to see which files got extracted.

Not so difficult when you use the long flag names. The flags all together in short: -xzvf.

https://www.cyberciti.biz/faq/linux-unix-bsd-extract-targz-file/

» talosctl

» Reboot

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talosctl reboot --wait

» Upgrade Talos

Upgrade to e.g. v1.3.0. Use --preserve when you are running a single node cluster.

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talosctl upgrade --image ghcr.io/siderolabs/installer:v1.3.0 --wait --debug --preserve

» Upgrade Kubernetes

When you upgrade the Talos version, it will not automatically upgrade the Kubernetes version. You have to do this in a separate step. For example, to upgrade Kubernetes to version 1.26.0:

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talosctl upgrade-k8s --to 1.26.0

» timeout

Kill a command after a specified duration:

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➜  ~ timeout 3s ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: icmp_seq=0 ttl=118 time=19.914 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=118 time=51.778 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=118 time=21.253 ms

Stop with SIGINT:

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➜  ~ timeout --signal SIGINT 3s ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: icmp_seq=0 ttl=118 time=20.661 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=118 time=19.799 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=118 time=20.925 ms

--- 8.8.8.8 ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 19.799/20.462/20.925/0.481 ms

Add --preserve-status to use the status of the invoked tool even when timeout kills it.

» ts

Add a timestamp to every output line:

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➜  ~ ping 8.8.8.8 | ts
Jun 13 18:09:11 PING 8.8.8.8 (8.8.8.8): 56 data bytes
Jun 13 18:09:11 64 bytes from 8.8.8.8: icmp_seq=0 ttl=118 time=19.638 ms
Jun 13 18:09:12 64 bytes from 8.8.8.8: icmp_seq=1 ttl=118 time=20.715 ms
Jun 13 18:09:13 64 bytes from 8.8.8.8: icmp_seq=2 ttl=118 time=19.597 ms

ts is part of the moreutils package.