How to 'strace' a systemd service on startup? #systemd #services #strace

https://askubuntu.com/q/1464285/612

this weird bug I'm running into is driving me mad, and it's unclear whether it's a #podman, #zfs, #strace, or #linux kernel bug. right now it's filed under buildah (the builder for podman) but in case anyone is curious:

https://github.com/containers/buildah/issues/4625

if anyone knowledgeable about this particular intersection of weird bugs can pitch in, it'll probably be interesting

TIL, but wish I hadn't: The utility for editing our product's configuration file will open the file 150 times to make a single change. And it reads the file an average of 23 times each time it's opened. #facepalm #strace

playing around with #strace and #kernel this afternoon

strace saves the day again!

I can't believe how incredibly useful it has been on the rare occasions I needed it. Probably saved me hours just now. Instead of digging into the source code of a library to figure out what was happening, I just traced the file accesses and found what files it was looking for before failing.

(FYI, strace traces the system calls programs make on Linux systems, so you can see what files they are reading and such)

#softwaredev #linux #strace

The cat is not really helping my debugging efforts (#c #strace #gdb #libpcap #wineoclock )

#Linux #Biodiversity #EasterEgg
> As der #Strauss is the #strace's mascot and also an #EndangeredSpecies,
> it is a strace's responsibility now to raise awareness about it.
strace -VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV

> After des Strausses awareness has been raised sufficiently,
> it is time for den Strauss to raise the awareness about strace,
> and to do so, the most modern and contemporary method has been elected:
> displaying tips, tricks and tweaks on each run.
https://github.com/strace/strace/commit/5a0e2dedfd99c056521552bf6089a0b073c5ac8f

RT @linuxaudit
Monitor file access by Linux processes https://linux-audit.com/monitor-file-access-by-linux-processes/ #lsof #strace #syscall

So that weird #pipe issue I saw with #Filespooler and used #strace to diagnose? Probably a #kernel #bug. https://changelog.complete.org/archives/10390-pipe-issue-likely-a-kernel-bug

At Your Command: Learn how the strace command can help you find files and troubleshoot programs https://buff.ly/31MRqel #Linux #OpenSource #CommandLine #strace #tools #networking

I thought I might spend some quarantine time translating my #firewall from #iptables to #nftables. The ip{,6}tables-restore-translate tools looked nice, and then I could tinker with the results until they fit my config automation.

Running them says "Permission denied (you must be root)", and then as root "Invalid argument". #strace shows nftables netlink calls. On a kernel without nftables, because I run iptables.

Man page says "these tools are text converters only". Great first impression.

Is it documented anywhere which SSH key a #RedHat #Satellite uses when running #Ansible?

Thanks to #strace I now know it's "/usr/share/foreman-proxy/.ssh/id_rsa_foreman_proxy", but I would have been much happier if it had said so in the documentation, for example in "Managing Hosts" part 2.8, "Running Ansible roles on a host".

Using #libsndfile to read #fft #windows from a #wav file, with a backwards seek to do analysis with #overlap, works great!

However, trying the same trick with an #ogg #vorbis input fails miserably: frame rate drops from 40+ to 3 after some minutes of audio-file time :( I conjecture (based on #top and #strace logs) that it is seeking back to the start of the file and re-decoding the whole thing on every seek backwards a little bit. Unsustainable.

Workaround: #ffmpeg to decompress beforehand.

@vu3rdd@octodon.social seems like it would be doable to reverse engineer such daemons by observing syscalls (eg using #strace)