module_4 task

tasks/module_4/task_2/data/2023-10-21-21-40-23-users.db.backup

@@ -0,0 +1,3 @@
+user_admin, admin
+user_second, basic
+andrea, user

tasks/module_4/task_2/data/users.db

@@ -0,0 +1,3 @@
+user_admin, admin
+user_second, basic
+andrea, user

tasks/module_4/task_2/scripts/db.sh

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+#!/bin/bash
+
+typeset fileName=users.db
+typeset fileDir=../data
+typeset filePath=$fileDir/$fileName
+
+# check/create db file
+if [[ "$1" != "help" && "$1" != "" && ! -f ../data/users.db ]];
+then
+    read -r -p "users.db does not exist. Do you want to create it? [Y/n] " answer
+    answer=${answer,,}
+    if [[ "$answer" =~ ^(yes|y)$ ]];
+    then
+        touch $fileName
+        echo "File ${fileName} is created."
+    else
+        echo "File ${fileName} must be created to continue. Try again." >&2
+        exit 1
+    fi
+fi
+
+function validateLatinLetters {
+  if [[ $1 =~ ^[A-Za-z_]+$ ]]; then return 0; else return 1; fi
+}
+
+function add {
+    read -p "Enter the username: " username
+
+    validateLatinLetters $username
+
+    if [[ "$?" == 1 ]];
+    then
+      echo "Name must only contain latin letters. Try again."
+      exit 1
+    fi
+
+    read -p "Enter the user role: " role
+
+    validateLatinLetters $role
+
+    if [[ "$?" == 1 ]]
+    then
+      echo "Role must only contains latin letters. Try again."
+      exit 1
+    fi
+
+    echo "${username}, ${role}" | tee -a $filePath
+}
+
+function backup {
+  backupFileName=$(date +'%Y-%m-%d-%H-%M-%S')-users.db.backup
+  cp $filePath $fileDir/$backupFileName
+
+  echo "Backup is created."
+}
+
+function restore {
+  latestBackupFile=$(ls $fileDir/*-$fileName.backup | tail -n 1)
+
+  if [[ ! -f $latestBackupFile ]]
+  then
+    echo "No backup file found."
+    exit 1
+  fi
+
+  cat $latestBackupFile > $filePath
+
+  echo "Backup is restored."
+}
+
+function find {
+    read -p "Enter username to search: " username
+
+    awk -F, -v x=$username '$1 ~ x' ../data/users.db
+
+    if [[ "$?" == 1 ]]
+    then
+        echo "User not found."
+        exit 1
+    fi
+}
+
+inverseParam="$2"
+function list {
+    if [[ $inverseParam == "inverse" ||  $inverseParam == "--inverse" ]] 
+    then
+      cat --number $filePath | tac
+    else
+      cat --number $filePath
+    fi
+}
+
+function help {
+    echo "Manages users in db. It accepts a single parameter with a command name."
+    echo
+    echo "Syntax: db.sh [command]"
+    echo
+    echo "List of available commands:"
+    echo
+    echo "add       Adds a new line to the users.db. Script must prompt user to type a
+                    username of new entity. After entering username, user must be prompted to
+                    type a role."
+    echo "backup    Creates a new file, named" $filePath".backup which is a copy of
+                    current" $fileName
+    echo "find      Prompts user to type a username, then prints username and role if such
+                    exists in users.db. If there is no user with selected username, script must print:
+                    “User not found”. If there is more than one user with such username, print all
+                    found entries."
+    echo "list      Prints contents of users.db in format: N. username, role
+                    where N – a line number of an actual record
+                    Accepts an additional optional parameter inverse which allows to get
+                    result in an opposite order – from bottom to top"
+}
+
+
+export $1
+case $1 in
+  add)            add ;;
+  backup)         backup ;;
+  restore)        restore ;;
+  find)           find ;;
+  list)           list ;;
+  help | '' | *)  help ;;
+esac