Why i cannot execute inxi Commands?

Why is it that I cannot execute an inxi command in the terminal

I assume you have installed it?

sudo apt-get install -y inxi

Once installed you should be able to run commands like.

inxi --recommends

What errors are you getting?

Yes is installed:

sudo apt-get install -y inxi
[sudo] Passwort für harald:         
Paketlisten werden gelesen... Fertig
Abhängigkeitsbaum wird aufgebaut.       
Statusinformationen werden eingelesen.... Fertig
inxi ist schon die neueste Version (2.3.56-1).
Die folgenden Pakete wurden automatisch installiert und werden nicht mehr benötigt:
  libsndfile1:i386 libwrap0:i386 ocl-icd-libopencl1:i386
Verwenden Sie »sudo apt autoremove«, um sie zu entfernen.
0 aktualisiert, 0 neu installiert, 0 zu entfernen und 0 nicht aktualisiert.

inxi --recommends
inxi will now begin checking for the programs it needs to operate. First a
check of the main languages and tools inxi uses. Python is only for debugging
data uploads unless Perl is missing.
---------------------------------------------------------------------------
Bash version: 4.4.20(1)-release
Gawk version: 4.1.4,
Sed version: 4.4
Sudo version: 1.8.21p2
Python version: 2.7.17 (legacy, no longer used)
Perl version: v5.26.1
---------------------------------------------------------------------------
Test One: Required System Directories (Linux Only).
If one of these system directories is missing, inxi cannot operate:

/proc.................................................... Present
/sys..................................................... Present

All the  directories are present.
---------------------------------------------------------------------------
Test Two: Required Core Applications.
If one of these applications is missing, inxi cannot operate:

df (info: partition data)................................ /bin/df
gawk (info: core tool)................................... /usr/bin/gawk
grep (info: string search)............................... /bin/grep
perl (info: debugger uploader; debugger /sys traverse)... /usr/bin/perl
lspci (info: hardware data).............................. /usr/bin/lspci
ps (info: process data).................................. /bin/ps
readlink................................................. /bin/readlink
sed (info: string replace)............................... /bin/sed
tr (info: character replace)............................. /usr/bin/tr
uname (info: kernel data)................................ /bin/uname
wc (info: word character count).......................... /usr/bin/wc

All the  applications are present.
---------------------------------------------------------------------------
Test Three: Script Recommends for Graphics Features.
NOTE: If you do not use X these do not matter (like a headless server).
Otherwise, if one of these applications is missing, inxi will have incomplete
output: 

glxinfo (info: -G glx info).............................. /usr/bin/glxinfo
xdpyinfo (info: -G multi screen resolution).............. /usr/bin/xdpyinfo
xprop (info: -S desktop data)............................ /usr/bin/xprop
xrandr (info: -G single screen resolution)............... /usr/bin/xrandr

All the  applications are present.
---------------------------------------------------------------------------
Test Four: Script Recommends for Remaining Features.
If one of these applications is missing, inxi will have incomplete output:

dig (info: -i wlan IP (Default))......................... /usr/bin/dig
dmidecode (info: -M if no sys machine data; -m memory)... /usr/sbin/dmidecode
file (info: -o unmounted file system).................... /usr/bin/file
hciconfig (info: -n -i bluetooth data-dev only-not used). /bin/hciconfig
hddtemp (info: -Dx show hdd temp)........................ /usr/sbin/hddtemp
ifconfig (info: -i ip lan-deprecated).................... /sbin/ifconfig
ip (info: -i ip lan)..................................... /sbin/ip
sensors (info: -s sensors output)........................ /usr/bin/sensors
strings (info: -I sysvinit version)...................... /usr/bin/strings
lsusb (info: -A usb audio;-N usb networking)............. /usr/bin/lsusb
modinfo (info: -Ax,-Nx module version)................... /sbin/modinfo
runlevel (info: -I runlevel)............................. /sbin/runlevel
sudo (info: -Dx hddtemp-user;-o file-user)............... /usr/bin/sudo
tree (info: -@1[1-5] debugger sys tree).................. Missing
uptime (info: -I uptime (check which package owns Debian)) /usr/bin/uptime

The following applications are missing from your system:

Application: tree
To add to your system, install the proper distribution package for your
system: 
Debian/Ubuntu: tree :: Arch Linux: tree :: Redhat/Fedora/Suse: tree
---------------------------------------------------------------------------
Test Five: Script Recommends for Remaining Features.
One of these downloaders needed for options -i/-w/-W (-U/-! [11-15], if
supported): 

curl (info: -i wan ip;-w/-W;-U/-! [11-15] [Default|OR]).. /usr/bin/curl
wget (info: -i wan ip;-w/-W;-U/-! [11-15] [OR]).......... /usr/bin/wget
perl (info: -i wan ip;-w/-W;-U/-! [11-15] [Module HTTP::Tiny]) /usr/bin/perl

All the  applications are present.
---------------------------------------------------------------------------
Test Six: System Directories for Various Information.
(Unless otherwise noted, these are for GNU/Linux systems)
If one of these directories is missing, inxi may have incomplete output:

/sys/class/dmi/id (info: -M system, motherboard, bios)... Present
/dev (info: -l,-u,-o,-p,-P,-D disk partition data)....... Present
/dev/disk/by-label (info: -l,-o,-p,-P partition labels).. Present
/dev/disk/by-uuid (info: -u,-o,-p,-P partition uuid)..... Present

All the  directories are present.
---------------------------------------------------------------------------
Test Seven: System Files for Various Information.
(Unless otherwise noted, these are for GNU/Linux systems)
If one of these files is missing, inxi may have incomplete output:

/proc/asound/cards (info: -A sound card data)............ Present
/proc/asound/version (info: -A ALSA data)................ Present
/proc/cpuinfo (info: -C cpu data)........................ Present
/etc/lsb-release (info: -S distro version data [deprecated]) Present
/proc/mdstat (info: -R mdraid data)...................... Present
/proc/meminfo (info: -I memory data)..................... Present
/etc/os-release (info: -S distro version data)........... Present
/proc/partitions (info: -p,-P partitions data)........... Present
/proc/modules (info: -G module data)..................... Present
/proc/mounts (info: -P,-p partition advanced data)....... Present
/var/run/dmesg.boot (info: -D,-d disk data [BSD only])... Missing
/proc/scsi/scsi (info: -D Advanced hard disk data [used rarely]) Present
/var/log/Xorg.0.log (info: -G graphics driver load status) Present

The following files are missing from your system:
File: /var/run/dmesg.boot
---------------------------------------------------------------------------
All tests completed.

I don’t know why he doesn’t use the commands from time to time or can’t execute them.

The only errors I see is that tree and /var/run/dmesg.boot are missing.

Tree can be installed using:

sudo apt install -y tree

What commands are run and fail, and fail with what message?