UC3M

Telematic/Audiovisual Syst./Communication Syst. Engineering

Systems Architecture

September 2017 - January 2018

Your work environment in Linux

Lab activities

Table of Contents

1. Directory management and information retrival
Readings
Work Plan
2. Processing cell logs
Resources
Work Plan

1.  Directory management and information retrival

Readings

Work Plan

You are a project boss in the SAUCEM Inc. company. In this company, the work is structured in groups. Each working group must do a set of projects, create a budget, do a set of activities, etc. In order to do this, each working group must be organized establishing a set of folders or directories in an structured manner, and locating their files into them correctly. In addition, each working group must have some mechanisms to obtain system information and remove some folders and files when needed.

As a project boss in the SAUCEM Inc. company, you are requested to write a set of Linux commands to create, and manage the folders and the system information that is related to you working group. Specifically, you must do 3 sub-tasks, which are described in detail below. It is important that you write all the commands that you execute in a text file, each command in one line, because you must submit this file at the end:

  1. Creation of a set of folders and files. In this task, you must execute a set of Linux commands for the creation of some directories and files with specific permissions.

    1. You must create the folder or directory structure that is indicated in the figure, and the directory “Working_Group” must be under the path /home/teleco. Execute the command sequence that is needed for that, taking into account that the directory initial location where you are in the system can be whatever, and the command sequence must work correctly with independency of the initial directory where you are located. In order to do this, you must use the commands mkdir and cd. Another mandatory requirement is that you must use the command mkdir using an absolute path in one of the commands but also a relative path in another command.

    2. Next, you must assign the proper permissions to each directory, so that you can have control about who can access these directories and with what permissions. All the directories must have read and execute permissions for the members of the owner's Linux group, and in addition write permissions for the directory owner, and none permissions for the rest. Moreover, there is an exception, for the directory Budget, permissions must be read, write and execution for the directory owner, and none permissions for the rest, because only the project boss is allowed to operate with the budget files. Execute the command sequence that is needed for assigning all of these permissions, taking into account that the directory initial location where you are in the system can be whatever, and the command sequence must work correctly with independency of the initial directory where you are located. In order to do this, you must use the commands chmod and cd. Another mandatory requirement is that you must use the command chmod using an absolute path in one of the commands but also a relative path in another command.

    3. Next, you must create a file description.txt under the directory P1 which must include inside the file the text “Project Description”. In order to achieve it, it is mandatory to use the command echo and the output redirection.

    4. Copy the file description.txt from the folder P1 to the folders P2 and P3, so that the file will also be present in these other folders. In order to achieve it, you must use the command cp.

    5. Copy the file description.txt also to the directory Budget, and to the directory Communication using the command cp. Next, change the name of the file that is under the directory Budget so that it is renamed into budget.ax, using the command mv. Next, replace completely the file text by the following text: “Budget file”. In order to achieve it, another requirement is that you must use the command echo and the output redirection.

    6. Move the file description.txt that is under the directory Communication, to the directory Others, and at the same time change its name so that the new name must be others.txt. For all of this, you must use the command mv. Next, replace completely the file text by the following text: “Other issues”. In order to achieve it, another requirement is that you must use the command echo and the output redirection.

    7. Using the command echo and the output redirection, modify the files “description.txt” that are under the directories P1, P2, and P3 , so that a blank space and the number 1, 2 or 3 repectively, are appended to the text that was in the file.

    8. For all the files that have been created, assign the same permissions as the directories that contain these files.

    9. Finally, put all the sequence of commands that you have done in a file called creation.sh with a text editor and save it. You must write a line for each one of the commands and in the same order that you did in this exercise. Futhermore, add the following text in the first line of the file:

      #!/bin/bash

      Assign permissions for the execution of the new created file. This new file that contains a command sequence is called script. If you execute this file from a command interpreter with ./creation.sh, then all the commands will be executed once in the established sequence. Therefore, if the same sequence of commands has to be executed later, then you will only have to execute the script this way, instead of typing everything, command by command.

  2. Generation of information.In this task, you must execute a set of linux commands for the generation of information about the created directory structure, the content of these files, and other system information

    1. First, execute the command date in order to show the present system date.

    2. Second, show the present directory where you are located, that can be whichever in general. To do this, use the command pwd.

    3. Show all the processes that are being executing in the Linux system in this moment. To do this, use the command ps.

    4. Using the commands cd and ls, show the information about the files and subdirectories that are under each one of the 8 folders of the working group. The information must show at least the file or/and directory creation date, their size, and permissions.

    5. Using the command grep, show all the files that contain the string “Project”, that are under some directory of the structure of the working group.

    6. Finally, put all the sequence of commands that you have done for the generation of information in a file called information.sh with a text editor and save it. You must write a line for each one of the commands and in the same order that you did in this exercise. Futhermore, add the following text in the first line of the file:

      #!/bin/bash

      Assign permissions for the execution of the new created file.

  3. Removal of folders and files. In this task you must execute a set of Linux command for the partial removal of the directory structure, as well as some files

    1. Remove completely all the files and directories that are under the directory Projects, including the same Project directory. You must do it using only the command rm

    2. Next, remove the file that is under the folder Others using the command rm.

    3. Next, remove the directory Others using the command rmdir. Note that this is possible because there is not already any files under the directory Others.

      Finally, put all the sequence of commands that you have done for the generation of information in a file called removal.sh with a text editor and save it. You must write a line for each one of the commands and in the same order that you did in this exercise. Futhermore, add the following text in the first line of the file:

      #!/bin/bash

      Assign permissions for the execution of the new created file.

How long did this activity take you? mins.

2.  Processing cell logs

Resources

Work Plan

You receive at SAUCEM Inc. a file with the logs that have been obtained by the mobile phone antenas (henceforth simply “cells”) surrounding Leganés during a week. Its format is plain text and it contains all the events of all the cell phones from any carrier within the range. Each file line contains an event, and the information is encoded with the following format:

You have to process this file using Linux commands to obtain detailed information.

  1. Decompress the file (read about the gunzip command.

  2. Show its content in the screen (read about the cat and more commands).

  3. Count the number of lines (thus the number of events) contained in the file (read about the wc command).

  4. Select from the file only those lines that have a given word (read about the grep command).

  5. We want to generate a report for each cell containing only the events that occurred in it. Create as many folders as needed to store these reports.

  6. If the symbol “>” is added at the end of a command followed by a file name, the produced data is stored in the file instead of shown on the screen. The file is newly created. If instead of “>” the command has “>>” followed by a file name, the content produced by the command is appended to the end of the given file.

    Using this functionality and the commands seen so far, create in each subfolder a file containing only the events that belong to that cell. Execute all the commands from the folder containing all the subfolders where the reports are stored.

  7. For each subfolder create a file summary.txt containing the following information in separated lines: number of events in the cell, number of events for each carrier, and number of events containing SMS operations.

    Execute the sequence of commands only for the first folder. Copy these commands in a text file using the editor. This file may now execute several times by the interpreter with the command:

    $ bash mycommands

    Use it to generate the summary.txt files in the remaining folders.

  8. Edit again the file with the commands. Add the following line at the top:

    #!/bin/bash

    Now use the chmod command to assign execution permission to its owner.

  9. Try to execute the file as a program with the command:

    $ ./mycommands

    This type of files containing commands for the interpreter are known as “scripts”.

  10. Try to execute the script without the “./” prefix. Why do you think is needed to execute the script?

How long did this activity take you? mins.
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