hanshenrik's questions

I see the following when running strace free:

hans@devad22:~$ strace free 2>&1 | grep openat
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libprocps.so.8", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libsystemd.so.0", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/liblzma.so.5", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libzstd.so.1", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/liblz4.so.1", O_RDONLY|O_CLOEXEC) = 3
(...)

Why is free opening a bunch of compression libraries? What does free need liblzma for?

what is the username/password combo for https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64-disk-kvm.img ? i have tried root:blank and ubuntu:blank and ubuntu:ubuntu , wasn't any of those. and fwiw i'm starting the image like this:

sudo qemu-system-x86_64 \
-machine accel=kvm \
-cpu host \
-smp cores=4 \
-m size=1G \
-serial stdio \
-boot menu=on,splash=/root/boot.bmp,splash-time=1000 \
-drive media=disk,file=jammy-server-cloudimg-amd64-disk-kvm.img,if=virtio,cache=unsafe,format=qcow2,werror=report

so strange, is ls multi-threaded somehow? what could ls possibly need libpthread for?

ldd /bin/ls
    linux-vdso.so.1 (0x00007ffff7fce000)
    libselinux.so.1 => /lib/x86_64-linux-gnu/libselinux.so.1 (0x00007ffff7f57000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ffff7d65000)
    libpcre2-8.so.0 => /usr/lib/x86_64-linux-gnu/libpcre2-8.so.0 (0x00007ffff7cd2000)
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ffff7ccc000)
    /lib64/ld-linux-x86-64.so.2 (0x00007ffff7fcf000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007ffff7ca9000)

running sensors -j -u i get, among other things,

{
   "coretemp-isa-0001":{
      "Adapter": "ISA adapter",
      "Core 0":{
         "temp2_input": 68.000,
         "temp2_max": 85.000,
         "temp2_crit": 95.000,
         "temp2_crit_alarm": 0.000
      }
   }
}

what's the difference between the "max" (85c) and "crit" (95c) temperatures?

this part of the output is for the CPU, and the CPU in question is Intel Xeon E5620

(i could GUESS that the "max" temp is where it starts thermal-throttling, and the "crit" temp is where it shuts down, but that's just a guess.)

How do I create a disabled account? for example when trying to login as nobody,

root@miniubuntu1804:/home/hans/projects/evaler/src# su nobody
This account is currently not available.

how do I create an account like that?

If I want to alias a executable file in /usr/local/bin , Is there a correct way to make such an alias? and how can I make one? Softlink? Hardlink? Something else?
For example, when I

apt-get install vim;

Aptitude will alias /usr/local/bin/vi as /usr/local/bin/vim (if I recall correctly)