Solve BSY week 4

2023-03-17 19:07:14 +01:00 · 2023-03-17 19:07:14 +01:00 · 6c33938885
commit 6c33938885
parent 8da8391f82
1 changed files with 373 additions and 0 deletions
--- a/Betriebssysteme/Week
+++ b/Betriebssysteme/Week
@ -0,0 +1,373 @@
+# Solutions
+## Table of Contents
+- [Solutions](#solutions)
+  - [Table of Contents](#table-of-contents)
+  - [Summary Display of `top`](#summary-display-of-top)
+  - [Processes `PID` `1` and `2`](#processes-pid-1-and-2)
+  - [Own Shell Process](#own-shell-process)
+  - [Showing off my Variables](#showing-off-my-variables)
+  - [Monitoring](#monitoring)
+  - [Job Control](#job-control)
+    - [What changed?](#what-changed)
+  - [Process Creation](#process-creation)
+
+## Summary Display of `top`
+Memory used, CPU used
+
+## Processes `PID` `1` and `2`
+
+| `PID` | Command    | Owner |
+| ----- | ---------- | ----- |
+| 1     | `systemd`  | root  |
+| 2     | `kthreadd` | root  |
+
+## Own Shell Process
+
+| `PID` | Command | Owner  |
+| ----- | ------- | ------ |
+| 8096  | `bash`  | ubuntu |
+
+## Showing off my Variables
+
+```bash
+printenv
+```
+
+```env
+SHELL=/bin/bash
+SESSION_MANAGER=local/ManuSurface:@/tmp/.ICE-unix/4052,unix/ManuSurface:/tmp/.ICE-unix/4052
+QT_ACCESSIBILITY=1
+COLORTERM=truecolor
+PYENV_SHELL=bash
+XDG_CONFIG_DIRS=/etc/xdg/xdg-pop:/etc/xdg
+SSH_AGENT_LAUNCHER=gnome-keyring
+XDG_MENU_PREFIX=gnome-
+GNOME_DESKTOP_SESSION_ID=this-is-deprecated
+GTK_IM_MODULE=ibus
+POSH_PID=8096
+GNOME_SHELL_SESSION_MODE=pop
+DOTNET_ROOT=/usr/lib/dotnet
+SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
+GRADLE_HOME=/home/manuel/.sdkman/candidates/gradle/current
+NVS_OS=linux
+NVS_USE_XZ=1
+SDKMAN_CANDIDATES_DIR=/home/manuel/.sdkman/candidates
+XMODIFIERS=@im=ibus
+DESKTOP_SESSION=pop
+GTK_MODULES=gail:atk-bridge
+PWD=/home/manuel
+PYENV_VIRTUALENV_INIT=1
+LOGNAME=manuel
+XDG_SESSION_DESKTOP=pop
+XDG_SESSION_TYPE=x11
+GPG_AGENT_INFO=/run/user/1000/gnupg/S.gpg-agent:0:1
+SYSTEMD_EXEC_PID=4075
+XAUTHORITY=/run/user/1000/gdm/Xauthority
+WINDOWPATH=2
+HOME=/home/manuel
+USERNAME=manuel
+LANG=en_US.UTF-8
+LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:
+XDG_CURRENT_DESKTOP=pop:GNOME
+VTE_VERSION=6800
+SDKMAN_VERSION=5.16.0
+CONDA_PROMPT_MODIFIER=false
+GNOME_TERMINAL_SCREEN=/org/gnome/Terminal/screen/41f216e0_74b7_4540_876a_34b9260733e4
+DOTNET_BUNDLE_EXTRACT_BASE_DIR=/home/manuel/.cache/dotnet_bundle_extract
+LESSCLOSE=/usr/bin/lesspipe %s %s
+XDG_SESSION_CLASS=user
+NVS_ROOT=/home/manuel/.nvs
+TERM=xterm-256color
+LESSOPEN=| /usr/bin/lesspipe %s
+LIBVIRT_DEFAULT_URI=qemu:///system
+USER=manuel
+GNOME_TERMINAL_SERVICE=:1.225
+NVS_HOME=/home/manuel/.nvs
+SDKMAN_DIR=/home/manuel/.sdkman
+DISPLAY=:1
+SHLVL=1
+QT_IM_MODULE=ibus
+SDKMAN_CANDIDATES_API=https://api.sdkman.io/2
+POSH_THEME=/home/manuel/.omp/manuel.omp.json
+XDG_RUNTIME_DIR=/run/user/1000
+GODOT4=godot
+PYENV_ROOT=/home/manuel/.pyenv
+XDG_DATA_DIRS=/usr/share/pop:/usr/share/gnome:/home/manuel/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop
+PATH=/home/manuel/.pyenv/plugins/pyenv-virtualenv/shims:/home/manuel/.pyenv/shims:/home/manuel/.pyenv/plugins/pyenv-virtualenv/shims:/home/manuel/.sdkman/candidates/gradle/current/bin:/home/manuel/.pyenv/plugins/pyenv-virtualenv/shims:/home/manuel/.pyenv/bin:/home/manuel/.nvs/default/bin:/home/manuel/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin:/home/manuel/.dotnet/tools
+GDMSESSION=pop
+DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
+SDKMAN_PLATFORM=linuxx64
+POWERLINE_COMMAND=oh-my-posh
+BASH_FUNC_nvs%%=() {  if [ -z "${NVS_HOME}" ]; then
+ export NVS_HOME="${NVS_ROOT}";
+ fi;
+ export NVS_POSTSCRIPT="${NVS_HOME}/nvs_tmp_$(dd if=/dev/urandom count=1 2> /dev/null | cksum | cut -f1 -d" ").sh";
+ local NODE_EXE="node";
+ if [ "${NVS_OS}" = "win" ]; then
+ NODE_EXE="node.exe";
+ fi;
+ local NODE_PATH="${NVS_HOME}/cache/${NODE_EXE}";
+ if [ ! -f "${NODE_PATH}" ]; then
+ local NODE_VERSION="$(grep '"bootstrap" *:' "${NVS_ROOT}/defaults.json" | sed -e 's/.*: *"//' -e 's/"[^\n]*//' -e 's/.*\///')";
+ local NODE_REMOTE="$(grep '"bootstrap" *:' "${NVS_ROOT}/defaults.json" | sed -e 's/.*: *"//' -e 's/"[^\n]*//' -e 's/\/.*//')";
+ local NODE_BASE_URI="$(grep "\"${NODE_REMOTE}\" *:" "${NVS_ROOT}/defaults.json" | sed -e 's/.*: *"//' -e 's/"[^\n]*//')";
+ local NODE_ARCHIVE_EXT=".tar.gz";
+ local TAR_FLAGS="-zxvf";
+ if [ "${NVS_OS}" = "win" ]; then
+ NODE_ARCHIVE_EXT=".7z";
+ else
+ if [ "${NVS_USE_XZ}" = "1" ]; then
+ NODE_ARCHIVE_EXT=".tar.xz";
+ TAR_FLAGS="-Jxvf";
+ fi;
+ fi;
+ local NODE_ARCH="$(uname -m | sed -e 's/x86_64/x64/;s/i86pc/x64/;s/i686/x86/;s/aarch64/arm64/')";
+ if [ "${NVS_OS}" = "aix" ]; then
+ NODE_ARCH="ppc64";
+ fi;
+ local NODE_FULLNAME="node-v${NODE_VERSION}-${NVS_OS}-${NODE_ARCH}";
+ local NODE_URI="${NODE_BASE_URI}v${NODE_VERSION}/${NODE_FULLNAME}${NODE_ARCHIVE_EXT}";
+ local NODE_ARCHIVE="${NVS_HOME}/cache/${NODE_FULLNAME}${NODE_ARCHIVE_EXT}";
+ if [ ! -d "${NVS_HOME}/cache" ]; then
+ command mkdir -p "${NVS_HOME}/cache";
+ fi;
+ echo "Downloading bootstrap node from ${NODE_URI}";
+ if type noglob > /dev/null 2>&1; then
+ noglob curl -L -# "${NODE_URI}" -o "${NODE_ARCHIVE}";
+ else
+ curl -L -# "${NODE_URI}" -o "${NODE_ARCHIVE}";
+ fi;
+ if [ ! -f "${NODE_ARCHIVE}" ] && [ "${NODE_ARCHIVE_EXT}" = ".tar.xz" ]; then
+ NODE_ARCHIVE_EXT=".tar.gz";
+ TAR_FLAGS="-zxvf";
+ NODE_ARCHIVE="${NVS_HOME}/cache/${NODE_FULLNAME}${NODE_ARCHIVE_EXT}";
+ echo "Retry download bootstrap node from ${NODE_URI} in gz format";
+ if type noglob > /dev/null 2>&1; then
+ noglob curl -L -# "${NODE_URI}" -o "${NODE_ARCHIVE}";
+ else
+ curl -L -# "${NODE_URI}" -o "${NODE_ARCHIVE}";
+ fi;
+ fi;
+ if [ ! -f "${NODE_ARCHIVE}" ]; then
+ echo "Failed to download node binary.";
+ return 1;
+ fi;
+ if [ "${NVS_OS}" = "win" ]; then
+ "${NVS_ROOT}/tools/7-Zip/7zr.exe" e "-o${NVS_HOME}/cache" -y "${NODE_ARCHIVE}" "${NODE_FULLNAME}/${NODE_EXE}" > /dev/null 2>&1;
+ else
+ if [ "${NVS_OS}" = "aix" ]; then
+ gunzip "${NODE_ARCHIVE}" | tar -xvC "${NVS_HOME}/cache" "${NODE_FULLNAME}/bin/${NODE_EXE}" > /dev/null 2>&1;
+ else
+ tar $TAR_FLAGS "${NODE_ARCHIVE}" -C "${NVS_HOME}/cache" "${NODE_FULLNAME}/bin/${NODE_EXE}" > /dev/null 2>&1;
+ fi;
+ mv "${NVS_HOME}/cache/${NODE_FULLNAME}/bin/${NODE_EXE}" "${NVS_HOME}/cache/${NODE_EXE}" > /dev/null 2>&1;
+ rm -r "${NVS_HOME}/cache/${NODE_FULLNAME}" > /dev/null 2>&1;
+ fi;
+ if [ ! -f "${NODE_PATH}" ]; then
+ echo "Failed to setup node binary.";
+ return 1;
+ fi;
+ echo "";
+ fi;
+ local EXIT_CODE=0;
+ case "$@" in 
+ "cd")
+ local DIR=$PWD;
+ while [ "$DIR" != "" -a ! \( -e "$DIR/.node-version" -o -e "$DIR/.nvmrc" \) ]; do
+ if [ "$DIR" = "/" ]; then
+ DIR=;
+ else
+ DIR=$(dirname "$DIR");
+ fi;
+ done;
+ if [ "$DIR" != "$NVS_AUTO_DIRECTORY" ]; then
+ command "${NODE_PATH}" "${NVS_ROOT}/lib/index.js" auto;
+ EXIT_CODE=$?;
+ fi;
+ export NVS_AUTO_DIRECTORY=$DIR
+ ;;
+ *)
+ command "${NODE_PATH}" "${NVS_ROOT}/lib/index.js" "$@";
+ EXIT_CODE=$?
+ ;;
+ esac;
+ if [ ${EXIT_CODE} = 2 ]; then
+ rm "${NODE_PATH}";
+ nvs $@;
+ fi;
+ if [ -f "${NVS_POSTSCRIPT}" ]; then
+ . "${NVS_POSTSCRIPT}";
+ command rm "${NVS_POSTSCRIPT}";
+ unset NVS_POSTSCRIPT;
+ fi;
+ return $EXIT_CODE
+}
+BASH_FUNC_nvsudo%%=() {  local NVS_CURRENT=`nvs which`;
+ if [ -n "${NVS_CURRENT}" ]; then
+ NVS_CURRENT=`dirname "${NVS_CURRENT}"`;
+ fi;
+ sudo "NVS_CURRENT=${NVS_CURRENT}" "${NVS_ROOT}/nvs" $*
+}
+_=/usr/bin/printenv
+```
+
+```bash
+export Name="Manuel"
+```
+
+## Monitoring
+```bash
+tail --follow /var/log/syslog
+```
+
+  - A message is logged stating that a new session has been started
+  - It is nested in a few `sshd` processes and a `bash` process
+  - The PID is `1375`, the state is "Sleeping"
+
+***Hierarchy:***
+
+```log
+├─sshd───sshd───sshd───bash───screen───screen─┬─bash───tail
+```
+
+  - The SSH session is terminated because the terminal running in it has been closed
+
+## Job Control
+Each syslog message is printed 3 times because 3 observers are running at the same time.
+
+### What changed?
+  - Job 2 is now the previous job (flagged with a `+`)
+  - Job 2 is stopped
+  - Job 2's command doesn't have an ampersand `&` at the end of it (probably because it is not running (in background))
+
+## Process Creation
+
+```bash
+size a.out
+```
+
+```
+   text	   data	    bss	    dec	    hex	filename
+   1565	    600	      8	   2173	    87d	a.out
+```
+
+```bash
+objdump -h a.out
+```
+
+```bash
+objdump -dj .text a.out
+```
+
+```c
+#include <stdio.h>
+#include <unistd.h>
+
+int main()
+{
+    fork();
+    sleep(30);
+    printf("My PID is: %d\n", getpid());
+    return 0;
+}
+```
+
+The virtual memory is identical, but their reserved memory is different.
+
+```c
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+int main()
+{
+    int pid = fork();
+    if (pid == 0)
+    {
+        sleep(1);
+        return 0;
+    }
+    else
+    {
+        int status = 0;
+        sleep(10);
+        waitpid(pid, &status, 0);
+        sleep(10);
+        return 0;
+    }
+}
+```
+
+Der Prozess verweilt im Zustand `Z` (Zombie) bis `waitpid()` ausgeführt wird.
+
+```c
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+int main()
+{
+    int pid = fork();
+    if (pid == 0)
+    {
+        sleep(10);
+        return 0;
+    }
+    else
+    {
+        return 0;
+    }
+}
+```
+
+Der Child-Prozess wird dem Prozess 1 (init) untergeordnet. Er wechselt nicht in den Zustand `Z`.
+
+```c
+#define _GNU_SOURCE
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#define STACK_SIZE (1024 * 1024) /* Stack size for cloned child */
+
+static int childFunc(void *arg)
+{
+    //do something
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    char *stack;
+    char *stackTop;
+    pid_t pid;
+
+    if (argc < 2)
+    {
+        fprintf(stderr, "Usage: %s <child-hostname>\n", argv[0]); // 1. Show help text if wrong amount of args
+        exit(EXIT_SUCCESS);
+    }
+
+    /* Create shared memory at address `stack` which is readable and writeable */
+    stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+
+    stackTop = stack + STACK_SIZE; // Store address to top of stack
+
+    /* Run `childFunc` in a new process with a new UTS that exits with exit code `SIGCHLD` */
+    pid = clone(childFunc, stackTop, CLONE_NEWUTS | SIGCHLD, argv[1]);
+
+    if (waitpid(pid, NULL, 0) == -1)
+    {
+        exit(EXIT_FAILURE); // Exit with non-zero exit code if child exits abnormally
+    }
+
+    printf("child has terminated\n");
+    exit(EXIT_SUCCESS); // Exit with zero exit code otherwise
+}
+```