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!
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 discovered a new sed trick today:
sed -i~
“I” stands for “in place”. It edits the files in place! And makes a backup if you want!
What’s in my container?
$ podman ps --ns CONTAINER ID NAMES PID CGROUPNS IPC MNT NET PIDNS USERNS UTS fe11359293e8 eloquent_austin 11090 4026532623 4026532621 4026532421 4026532624 4026531837 4026532622
$ sudo ls -l /proc/11090/root/
total 22628
lrwxrwxrwx. 1 root root 7 Jul 25 2019 bin -> usr/bin
dr-xr-xr-x. 2 root root 6 Jul 25 2019 boot
drwxr-xr-x. 5 root root 360 Jan 24 12:03 dev
drwxr-xr-x. 1 root root 183 Jan 23 16:43 etc
...
Thank you.
[28 Jan@1135UTC] UPDATE—Actually, this doesn’t seem to work with newer systems, sorry!
Every couple days something on my RHEL 7 box goes into a swapstorm and uses up all the memory. I think it’s Firefox, but I never figured out why, generally I have four different Firefoxes running with four different profiles, so it’s hard to tell which one’s failing (if it even is that). Anyway, sometimes it makes the screen lock crash or something, and I can’t get in, and I can never remember what process you have to kill to get back in, so here it is: gnome-shell. You have to killall -9 gnome-shell, and it lets you back in. Also killall -STOP firefox and killall -STOP "Web Content" are handy if the swapstorm is still under way.