diff --git a/.github/workflows/gradle.yml b/.github/workflows/gradle.yml
index eafb6a9..388e42b 100644
--- a/.github/workflows/gradle.yml
+++ b/.github/workflows/gradle.yml
@@ -3,11 +3,7 @@
 
 name: Java CI with Gradle
 
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
+on: [push, pull_request]
 
 jobs:
   build:
@@ -16,26 +12,19 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up JDK 1.8
+    - name: Set up JDK 11
       uses: actions/setup-java@v1
       with:
-        java-version: 1.8
+        java-version: 11
+        
     - name: Grant execute permission for gradlew
-      run: chmod +x gradlew
+      run: chmod +x ./gradlew
+      
+    - name: Run command
+      run: echo Hello
+      
     - name: Build with Gradle
       run: ./gradlew build
-  
-  test:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up JDK 1.8
-      uses: actions/setup-java@v1
-      with:
-        java-version: 1.8
-    - name: Grant execute permission for gradlew
-      run: chmod +x gradlew
-    - name: Test with Gradle
+     
+    - name: Test with Gradlew
       run: ./gradlew test
diff --git a/build.gradle.kts b/build.gradle.kts
new file mode 100644
index 0000000..bd7cd2b
--- /dev/null
+++ b/build.gradle.kts
@@ -0,0 +1,42 @@
+plugins {
+    java
+    application
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation("org.jetbrains:annotations:16.0.2")
+    testImplementation(platform("org.junit:junit-bom:5.7.0"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+}
+
+java {
+    sourceSets {
+        main {
+            java.setSrcDirs(listOf("src/main/java"))
+            resources.setSrcDirs(listOf("src/resources"))
+        }
+        test {
+            java.setSrcDirs(listOf("src/test/java"))
+        }
+    }
+}
+
+tasks.getByName<JavaExec>("run") {
+    standardInput = System.`in`
+}
+
+application{
+    mainClass.set("commandline.CommandLine")
+}
+
+tasks.compileJava {
+    options.release.set(11)
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..e708b1c
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..be52383
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100755
index 0000000..cd77b62
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,185 @@
+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1.txt to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=`expr $i + 1`
+    done
+    case $i in
+        0) set -- ;;
+        1.txt) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..ac1b06f
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000..2a591ed
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,2 @@
+rootProject.name = 'CLI'
+
diff --git a/src/main/java/commandline/CommandLine.java b/src/main/java/commandline/CommandLine.java
new file mode 100644
index 0000000..324bbbc
--- /dev/null
+++ b/src/main/java/commandline/CommandLine.java
@@ -0,0 +1,88 @@
+package commandline;
+
+import commandline.commands.Command;
+import commandline.utils.CommandBuilder;
+import commandline.utils.Parser;
+import commandline.utils.ShellCommand;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+/*
+  Main Class
+    until get "exit":
+     read the line, split it by |,
+     send each part to the parser,
+     get the command name and arguments,
+     send the name to the commandBuilder,
+     then execute the command by run method
+*/
+public class CommandLine {
+    private static final List<String> results = new ArrayList<>();
+
+    // main function for CommandLine
+    private static String work(InputStream inputStream) {
+        Scanner scanner = new Scanner(inputStream);
+        boolean cycle = true;
+        StringBuilder output = new StringBuilder();
+        while (cycle) {
+            String userInput = scanner.nextLine();
+            String[] commands = userInput.split("\\s*\\|\\s*");
+            for (String str : commands) {
+                List<String> list = Parser.parse(str);
+                if (!list.isEmpty()) {
+                    if (list.get(0).matches("exit")) {
+                        cycle = false;
+                        break;
+                    }
+                    Command command = CommandBuilder.getCommand(list.get(0));
+                    if (command == null) {
+                        try {
+                            StringBuilder input = new StringBuilder();
+                            for (String elem : list) {
+                                input.append(elem);
+                            }
+                            String res = ShellCommand.executeCommand(input.toString());
+                            results.add(res);
+                            if (res.isEmpty()) {
+                                output.append("Wrong command: ").append(input);
+                                System.out.println("Wrong command: " + input);
+                                break;
+                            }
+                        } catch (InterruptedException | IOException e) {
+                            output.append("Wrong command: ").append(list.get(0)).append("\n");
+                            System.out.println("Wrong command: " + list.get(0));
+                            break;
+                        }
+                    } else {
+                        List<String> s = list.subList(1, list.size());
+                        if (!results.isEmpty()) {
+                            String before = results.remove(results.size() - 1);
+                            results.add(command.run(s, before));
+                        } else {
+                            results.add(command.run(s, ""));
+                        }
+                    }
+                }
+            }
+            if (!results.isEmpty()) {
+                String result = results.remove(0);
+                output.append(result).append("\n");
+                System.out.println(result);
+            }
+        }
+        return output.toString();
+    }
+
+    public static void main(String[] args) {
+        work(System.in);
+    }
+
+    // func only for test
+    public static String forTest(InputStream input) {
+        return work(input);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/commandline/commands/Cat.java b/src/main/java/commandline/commands/Cat.java
new file mode 100644
index 0000000..caceabd
--- /dev/null
+++ b/src/main/java/commandline/commands/Cat.java
@@ -0,0 +1,34 @@
+package commandline.commands;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.List;
+
+/* Function Cat
+ * if the command hasn't received any args, then it returns previous
+ * calculation, else returns the contents of args
+ */
+public class Cat implements Command {
+    @Override
+    public String run(List<String> args, String before) {
+        if (args.isEmpty()) {
+            return before;
+        }
+        StringBuilder output = new StringBuilder();
+        for (String str : args) {
+            if (!str.equals(" ")) {
+                try (BufferedReader br = new BufferedReader(new FileReader(str))) {
+                    String line;
+                    while ((line = br.readLine()) != null) {
+                        output.append(line);
+                        output.append("\n");
+                    }
+                } catch (IOException e) {
+                    return "File not found";
+                }
+            }
+        }
+        return output.deleteCharAt(output.length() - 1).toString();
+    }
+}
diff --git a/src/main/java/commandline/commands/Command.java b/src/main/java/commandline/commands/Command.java
new file mode 100644
index 0000000..a53b9e6
--- /dev/null
+++ b/src/main/java/commandline/commands/Command.java
@@ -0,0 +1,11 @@
+package commandline.commands;
+
+import java.util.List;
+
+/* Interface for all commands with a single method,
+ * that executes the command
+ */
+public interface Command {
+    // takes args and result of previous calculation
+    String run(List<String> args, String before);
+}
\ No newline at end of file
diff --git a/src/main/java/commandline/commands/Echo.java b/src/main/java/commandline/commands/Echo.java
new file mode 100644
index 0000000..ce3f323
--- /dev/null
+++ b/src/main/java/commandline/commands/Echo.java
@@ -0,0 +1,22 @@
+package commandline.commands;
+
+import java.util.List;
+
+/* Function echo
+ * if it has args then returns them
+ * else returns empty string
+ */
+public class Echo implements Command {
+    @Override
+    public String run(List<String> args, String before) {
+        if (args.isEmpty()) {
+            return "";
+        }
+        StringBuilder result = new StringBuilder();
+        for (String s : args) {
+            result.append(s).append(" ");
+        }
+        result.deleteCharAt(result.length()-1);
+        return result.toString();
+    }
+}
diff --git a/src/main/java/commandline/commands/Pwd.java b/src/main/java/commandline/commands/Pwd.java
new file mode 100644
index 0000000..426236e
--- /dev/null
+++ b/src/main/java/commandline/commands/Pwd.java
@@ -0,0 +1,11 @@
+package commandline.commands;
+
+import java.util.List;
+
+//returns user.dir
+public class Pwd implements Command {
+    @Override
+    public String run(List<String> args, String before) {
+        return System.getProperty("user.dir");
+    }
+}
diff --git a/src/main/java/commandline/commands/Wc.java b/src/main/java/commandline/commands/Wc.java
new file mode 100644
index 0000000..01fbd23
--- /dev/null
+++ b/src/main/java/commandline/commands/Wc.java
@@ -0,0 +1,80 @@
+package commandline.commands;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+
+/* Function wc
+ * if it has arguments, then it counts the number of lines, words and bytes in files
+ * else it counts the same in result of previous calculations
+ */
+public class Wc implements Command {
+    private long totalByteCount = 0;
+    private long totalLineCount = 0;
+    private long totalWordCount = 0;
+    private long wordCount = 0;
+    private long lineCount = 0;
+    private long byteCount = 0;
+
+    // counts all in result of previous calculations
+    private String countArgsEmpty(String before) {
+        byte[] b = before.getBytes(StandardCharsets.UTF_8);
+        byteCount = b.length;
+        wordCount = before.replaceAll("\\s{2,}", " ").trim().split("\\s").length;
+        lineCount = before.chars().filter(ch -> ch == '\n').count() + 1;
+        return lineCount + "  " + wordCount + "  " + (byteCount + 1);
+    }
+
+    // counts all in files
+    private String countArgsNoEmpty(List<String> args) {
+        StringBuilder result = new StringBuilder();
+        for (String s : args) {
+            if (!s.equals(" ")) {
+                wordCount = 0;
+                lineCount = 0;
+                File f = new File(s);
+                byteCount = f.length();
+                totalByteCount += byteCount;
+                try (BufferedReader br = new BufferedReader(new FileReader(s))) {
+                    String line;
+                    while ((line = br.readLine()) != null) {
+                        if (!line.isEmpty()) {
+                            wordCount += line.trim().split("\\s+").length;
+                        }
+                        lineCount += 1;
+                    }
+                } catch (IOException e) {
+                    return "wc: "+ s + ": No such file or directory";
+                }
+                totalLineCount += lineCount;
+                totalWordCount += wordCount;
+                result.append(lineCount).append("  ");
+                result.append(wordCount).append("  ");
+                result.append(byteCount).append(" ");
+                if (args.size() > 1) {
+                    result.append(s).append("\n");
+                } else {
+                    result.append(s);
+                }
+            }
+        }
+        if (args.size() == 1)
+            return result.toString();
+        result.append(totalLineCount).append("  ");
+        result.append(totalWordCount).append("  ");
+        result.append(totalByteCount).append(" total");
+        return result.toString();
+    }
+
+    @Override
+    // main function
+    public String run(List<String> args, String before) {
+        if (args.isEmpty()) {
+            return countArgsEmpty(before);
+        }
+        return countArgsNoEmpty(args);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/commandline/utils/CommandBuilder.java b/src/main/java/commandline/utils/CommandBuilder.java
new file mode 100644
index 0000000..1b0f0a6
--- /dev/null
+++ b/src/main/java/commandline/utils/CommandBuilder.java
@@ -0,0 +1,26 @@
+package commandline.utils;
+
+import commandline.commands.*;
+
+/* Takes command's name
+ * if command is found then returns the instance of the command class
+ * else returns null
+ */
+public class CommandBuilder {
+    private CommandBuilder() {
+    }
+
+    public static Command getCommand(String commandName) {
+        if (commandName.equals("pwd")) {
+            return new Pwd();
+        } else if (commandName.equalsIgnoreCase("cat")) {
+            return new Cat();
+        } else if (commandName.equalsIgnoreCase("echo")) {
+            return new Echo();
+        } else if (commandName.equalsIgnoreCase("wc")) {
+            return new Wc();
+        } else {
+            return null;
+        }
+    }
+}
diff --git a/src/main/java/commandline/utils/Parser.java b/src/main/java/commandline/utils/Parser.java
new file mode 100644
index 0000000..4affcad
--- /dev/null
+++ b/src/main/java/commandline/utils/Parser.java
@@ -0,0 +1,80 @@
+package commandline.utils;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/*
+ * Class for parsing commands using regular expressions
+*/
+public class Parser {
+    private static final Variables variables = new Variables();
+    private static final Set<String> commands = Set.of("echo", "wc", "pwd", "exit", "cat");
+
+    private Parser() {
+    }
+
+    //parse string in " "
+    private static String parseInQuotes(String input) {
+        StringBuilder resultS = new StringBuilder(input.replaceAll("\"", ""));
+        int i = 0;
+        while (i < resultS.length()) {
+            int d = resultS.indexOf("$");
+            if (d != -1 && d != resultS.length() - 1) {
+                for (i = d + 1; i < resultS.length(); i++) {
+                    if (resultS.charAt(i) == ' ' || resultS.charAt(i) == '\'') {
+                        break;
+                    }
+                }
+                String var = resultS.substring(d + 1, i);
+                resultS.replace(d, i, variables.getVar(var));
+            } else {
+                break;
+            }
+        }
+        return resultS.toString();
+    }
+
+    // main function for parsing
+    public static List<String> parse(String str) {
+        List<String> list = new ArrayList<>();
+        Matcher m = Pattern.compile("(\\w+=\\w+)|('.+')|(\".+\")|(\\S+)|(\\$\\w+)").matcher(str);
+        while (m.find()) {
+            String currentS = m.group(0);
+            if (currentS.charAt(0) == '\'' && currentS.charAt(m.group(0).length() - 1) == '\'') {
+                list.add(currentS.substring(1, currentS.length() - 1));
+            } else if (currentS.matches("\\w+=\\w+")) {
+                String[] split = currentS.split("=");
+                variables.putVar(split[0], split[1]);
+            } else if (currentS.matches("\\$\\w+(\\$\\w+)*")) {
+                String[] vars = currentS.split("\\$");
+                if (vars.length > 2) {
+                    StringBuilder maybeCommand = new StringBuilder();
+                    for (String one : vars) {
+                        if (!one.isEmpty()) {
+                            maybeCommand.append(variables.getVar(one));
+                        }
+                    }
+                    list.add(maybeCommand.toString());
+                }
+                else {
+                    list.add(variables.getVar(currentS.substring(1)));
+                }
+            } else if (currentS.charAt(0) == '\"' && currentS.charAt(currentS.length() - 1) == '\"') {
+                list.add(parseInQuotes(currentS));
+            } else if (commands.contains(m.group(0))) {
+                list.add(m.group(0));
+            } else {
+                list.add(m.group(0));
+                list.add(" ");
+            }
+        }
+        if (!list.isEmpty() && list.get(list.size() - 1).equals(" ")) {
+            list.remove(list.size() - 1);
+        }
+
+        return list;
+    }
+}
diff --git a/src/main/java/commandline/utils/ShellCommand.java b/src/main/java/commandline/utils/ShellCommand.java
new file mode 100644
index 0000000..83538eb
--- /dev/null
+++ b/src/main/java/commandline/utils/ShellCommand.java
@@ -0,0 +1,27 @@
+package commandline.utils;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+/* Class for running shell commands */
+public class ShellCommand {
+    private ShellCommand() {
+    }
+
+    public static String executeCommand(String command) throws IOException, InterruptedException {
+        StringBuilder output = new StringBuilder();
+        Process p = Runtime.getRuntime().exec(command);
+        p.waitFor();
+        try (
+                BufferedReader reader =
+                        new BufferedReader(new InputStreamReader(p.getInputStream()))
+        ) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                output.append(line).append("\n");
+            }
+        }
+        return output.toString();
+    }
+}
diff --git a/src/main/java/commandline/utils/Variables.java b/src/main/java/commandline/utils/Variables.java
new file mode 100644
index 0000000..88cf193
--- /dev/null
+++ b/src/main/java/commandline/utils/Variables.java
@@ -0,0 +1,17 @@
+package commandline.utils;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/* Class for storing variables */
+public class Variables {
+    private final Map<String, String> vars = new HashMap<>();
+
+    public void putVar(String name, String value) {
+        vars.put(name, value);
+    }
+
+    public String getVar(String name) {
+        return vars.getOrDefault(name, "");
+    }
+}
diff --git a/src/test/java/commandline/CommandLineTest.java b/src/test/java/commandline/CommandLineTest.java
new file mode 100644
index 0000000..64c5dee
--- /dev/null
+++ b/src/test/java/commandline/CommandLineTest.java
@@ -0,0 +1,135 @@
+package commandline;
+
+import commandline.utils.ShellCommand;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+
+// Testing
+class CommandLineTest {
+    // helper
+    private String out(String input) {
+        ByteArrayInputStream in = new ByteArrayInputStream(input.getBytes());
+        System.setIn(in);
+        return CommandLine.forTest(in);
+    }
+
+    /* Test echo
+     * echo 12345
+     * echo '123 45'
+     * a=10; echo $a
+     * a=10; echo "a = $a"
+     * a=10; b=100; echo  echo "a = $a and b = $b and c ==  end"
+     * echo
+     * echo 10 | echo 20
+     * echo 10 | wc
+     * echo 10 | pwd
+     * echo 10 | cat
+     * x=10  echo "aasd'$x'asd" == "aasd'10'asd"
+     * echo "aasd'$c'asd" == "aasd''asd"
+     * */
+    @Test
+    void testEcho() throws IOException, InterruptedException {
+        String input = "echo 12345 \n exit";
+        Assertions.assertEquals("12345\n", out(input));
+        input = "echo '123 45' \n exit";
+        Assertions.assertEquals("123 45\n", out(input));
+        input = "a=10 \n echo $a \n exit";
+        Assertions.assertEquals("10\n", out(input));
+        input = "a=10 \n echo \"a = $a\" \n exit";
+        Assertions.assertEquals("a = 10\n", out(input));
+        input = "a=10 \n b=100 \n echo \"a = $a and b = $b and c ==  end\" \n exit";
+        Assertions.assertEquals("a = 10 and b = 100 and c ==  end\n", out(input));
+        input = "echo \n exit";
+        Assertions.assertEquals("\n", out(input));
+        input = "echo 10 | echo 20 \n exit";
+        Assertions.assertEquals("20\n", out(input));
+        input = "echo 10 | wc \n exit";
+        Assertions.assertEquals("1  1  3\n", out(input));
+        input = "echo 10 | pwd \n exit";
+        Assertions.assertEquals(ShellCommand.executeCommand("pwd"), out(input));
+        input = "echo 10 | cat \n exit";
+        Assertions.assertEquals("10\n", out(input));
+        input = "x=10 \n echo \"aasd'$x'asd\"\n exit";
+        Assertions.assertEquals("aasd'10'asd\n", out(input));
+        input = "echo \"aasd'$c'asd\"\n exit";
+        Assertions.assertEquals("aasd''asd\n", out(input));
+        System.setIn(System.in);
+    }
+
+    /*Test variables
+    * a=p b=wd $a$b == command pwd
+    * a=ec b=ho $a$b 5 == echo 5 == 5
+    * a=ec b=ho echo $a$b == echo echo == echo
+    * a=ec b=ho echo $a $b == echo ec ho == ec ho
+    * */
+    @Test
+    void testVars() throws IOException, InterruptedException {
+        String input = "a=p \n b=wd \n $a$b \n exit";
+        Assertions.assertEquals(ShellCommand.executeCommand("pwd"), out(input));
+        input = "a=ec \n b=ho \n $a$b 5 \n exit";
+        Assertions.assertEquals("5\n", out(input));
+        input = "a=ec \n b=ho \n echo $a$b \n exit";
+        Assertions.assertEquals("echo\n", out(input));
+        input = "a=ec \n b=ho \n echo $a $b \n exit";
+        Assertions.assertEquals("ec ho\n", out(input));
+        System.setIn(System.in);
+    }
+
+    /* Test pwd */
+    @Test
+    void testPwd() throws IOException, InterruptedException {
+        String input = "pwd \n exit";
+        Assertions.assertEquals(ShellCommand.executeCommand("pwd"), out(input));
+        System.setIn(System.in);
+    }
+
+    /* Test cat
+     * cat gradlew.bat
+     * cat 1.txt 123.txt
+     * cat go wrong
+     * */
+    @Test
+    void testCat() throws IOException, InterruptedException {
+        String input = "cat gradlew.bat \n exit";
+        Assertions.assertEquals(ShellCommand.executeCommand(input), out(input));
+        input = "cat testFiles/1.txt testFiles/123.txt \n exit";
+        Assertions.assertEquals(ShellCommand.executeCommand(input), out(input));
+        input = "cat nofile.nofile \n exit";
+        Assertions.assertEquals("File not found\n", out(input));
+        System.setIn(System.in);
+    }
+
+    /*
+     * wc gradlew.bat
+     * wc 1.txt 123.txt
+     * cat 1.txt | wc
+     * wc ololo  ==  wc: ololo: No such file or directory
+     * */
+    @Test
+    void testWc() {
+        String input = "wc gradlew.bat \n exit";
+        Assertions.assertEquals("89  357  2763 gradlew.bat\n", out(input));
+        input = "wc testFiles/1.txt testFiles/123.txt \n exit";
+        Assertions.assertEquals("3  3  6 testFiles/1.txt\n" + "3  3  25 testFiles/123.txt\n" +
+                "6  6  31 total\n", out(input));
+        input = "cat testFiles/1.txt | wc \n exit";
+        Assertions.assertEquals("3  3  6\n", out(input));
+        System.setIn(System.in);
+        input = "wc ololo \n exit";
+        Assertions.assertEquals("wc: ololo: No such file or directory\n"
+                , out(input));
+    }
+
+    // Test commands which is not in the project
+    @Test
+    void testOtherCommands() {
+        String input = "python \n exit";
+        Assertions.assertEquals("Wrong command: python\n", out(input));
+        System.setIn(System.in);
+        input = "git lolol \n exit";
+        Assertions.assertEquals("Wrong command: git lolol\n", out(input));
+    }
+}
diff --git a/testFiles/1.txt b/testFiles/1.txt
new file mode 100644
index 0000000..01e79c3
--- /dev/null
+++ b/testFiles/1.txt
@@ -0,0 +1,3 @@
+1
+2
+3
diff --git a/testFiles/123.txt b/testFiles/123.txt
new file mode 100644
index 0000000..692827c
--- /dev/null
+++ b/testFiles/123.txt
@@ -0,0 +1,3 @@
+laskjdlask
+asdasdasd
+123