Do you need a thread-safe atomic counter in Python? Use itertools.count():
>>> from itertools import count >>> counter = count() >>> next(counter) 0 >>> next(counter) 1 >>> next(counter) 2
I found this in the decorator package, labelled Atomic get-and-increment provided by the GIL
. So simple! So cool!
Did you forget the -r when cloning a git repo with submodules? The command you’re looking for is git submodule update --init
Have you written a Docker Registry API client in GitLab CI/CD YAML? I have.
# Delete candidate image from CI repository. clean-image: stage: .post except: - main variables: AUTH_API: "$CI_SERVER_URL/jwt/auth" SCOPE: "repository:$CI_PROJECT_PATH" REGISTRY_API: "https://$CI_REGISTRY/v2/$CI_PROJECT_PATH" before_script: - > which jq >/dev/null || (sudo apt-get update && sudo apt-get -y install jq) script: - echo "Deleting $CANDIDATE_IMAGE" - > TOKEN=$(curl -s -u "$CI_REGISTRY_USER:$CI_REGISTRY_PASSWORD" "$AUTH_API?service=container_registry&scope=$SCOPE:delete,pull" | jq -r .token) - > DIGEST=$(curl -s -I -H "Authorization: Bearer $TOKEN" -H "Accept: application/vnd.docker.distribution.manifest.v2+json" "$REGISTRY_API/manifests/$CI_COMMIT_SHORT_SHA" | tr -d "\r" | grep -i "^docker-content-digest: " | sed "s/^[^:]*: *//") - > curl -s -X DELETE -H "Authorization: Bearer $TOKEN" "$REGISTRY_API/manifests/"$(echo $DIGEST | sed "s/:/%3A/g")
Need to redirect to a file from sudo? Use sudo tee >/dev/null:
$ sudo ls -l /root >/root/files.list -bash: /root/files.list: Permission denied $ sudo ls -l /root | sudo tee /root/files.list >/dev/null $ sudo ls -l /root/files.list -rw-r--r-- 1 root root 94 Oct 18 09:31 /root/files.list
Do you want to tee the output of a command to a file, but see it in your terminal too, without buffering? The stdbuf command can do this for you:
$ sudo stdbuf --output=L tcpdump -i any -tttt -n 'udp port 5353' | tee -a tcpdump-mdns
tcpdump: data link type LINUX_SLL2
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
2023-06-15 11:55:16.637670 eth0 M IP 10.0.0.23.5353 > 224.0.0.251.5353: 0 A (QM)? winnebago.local. (28)
2023-06-15 11:55:16.744660 eth0 M IP 10.0.0.42.5353 > 224.0.0.251.5353: 0*- [0q] 1/0/0 (Cache flush) A 10.0.0.42 (38)
...
$ apt-file find guestmount guestmount: /usr/bin/guestmount guestmount: /usr/share/bash-completion/completions/guestmount guestmount: /usr/share/doc/guestmount/changelog.Debian.gz guestmount: /usr/share/doc/guestmount/copyright guestmount: /usr/share/man/ja/man1/guestmount.1.gz guestmount: /usr/share/man/man1/guestmount.1.gz guestmount: /usr/share/man/uk/man1/guestmount.1.gz
Are you writing a script and some command doesn’t accept hostnames and you don’t want to inline the IP address? dig +short is your friend!
$ dig +short gbenson.net 69.163.152.201
$ apt policy wget
wget:
Installed: 1.21.2-2ubuntu1
Candidate: 1.21.2-2ubuntu1
Version table:
*** 1.21.2-2ubuntu1 500
500 http://gb.archive.ubuntu.com/ubuntu jammy/main amd64 Packages
100 /var/lib/dpkg/status
By the way, if you’ve never used Python’s debugger, it really is as simple as adding a call to the built-in function breakpoint() at the point you want it to stop.
I had a play with Elastic Beanstalk the other day. It’s one of those things people turn their noses up at, but it seems pretty good for prototyping and small things. My biggest issue so far has been that, for Python applications, it expects a WSGI callable called application in the file application.py… but I was using Flask, and every single Flask application ever has a WSGI callable called app in the file app.py. I tried to not care, but it got too much after about an hour so I went and found how to override it:
$ cat .ebextensions/01_wsgi.config
option_settings:
aws:elasticbeanstalk:container:python:
WSGIPath: "app:app"
Thank you Nik Tomazic for that! (=⌒‿‿⌒=)