Linux Command Line: Essential Operations and Scripting

Posted on Jan 26, 2025 in Business Sciences

1. Relationships:

1: fg% 3-D – Mounted disk
2: B – gzip-compressed
3: unmount – Nothing
4: mke3fs -C – Format
5: tar – Nothing
6: dd if-E – To back up
7: bg% 3 -F – Passing the task
8: tar cvf-A – To package

2. Commands:

A: 2 + 2 = expr 2 + 2
B: Change user password: passwd ana
C: Shut down computer: shutdown -h now
D: Change ownership of ejer60 to user antonio: chown antonio ejer60
E: Delete all files: rm *
F: Change the file name: mv script52 ejer52
G: Copy all files starting with “exercise” to the “Exercise” directory: cp exercise* Exercise/
H: Display full path: pwd
I: Search for lines containing “/bin/bash” in all files in the current directory: grep "/bin/bash" *
J: Look in /etc for files starting with “pro”: find /etc/ -name pro*

3. Permissions:

After executing ls -l ejer52, to give read, write, and execute permissions only to the user on this file, use the following command:

chmod 700 ejer52

5. Definitions:

A: PS1-5 – Defines the prompt
B: HOME-4 – User’s home directory
C: Background process-1 – Does not receive any signal from the terminal
D: MANPATH-3 – Specifies the manual page search path
E: Foreground process-2 – Receives input from the terminal

6. Terminating a Process:

To terminate a process that is not responding, you can use the following steps:

Open the console as root or the user who owns the process.
Run ps -aux to list all processes and find the process ID (PID).
Terminate the process using kill -9 PID, replacing PID with the actual process ID.

8. Running a Script:

To run a script located in the current directory, you can include the current directory (.) in the PATH environment variable.

9. Packaging and Compressing Files:

To package the contents of /home/angeles/exercises and compress it into /home/angeles/copies/copia.tar.gz, use the following command:

tar cvf - /home/angeles/exercises | gzip -9c > /home/angeles/copies/copia.tar.gz

10. Command Output:

A: After executing ls /win | sort > result, the file “result” will contain the sorted contents of the /win directory.
B: If the /win directory is empty or does not exist, the command would show nothing, and the “result” file would be empty.

11. chmod Examples:

A: chmod a+r is equivalent to chmod 444 (read permission for everyone)
B: chmod 666 is equivalent to chmod uog+w (read and write permission for everyone)

12. Command Classification:

cp – Yes
yast – No
halt – Yes
cat – No
useradd – Yes

13. Directory Functions:

A: /bin – Stores essential system executable files
B: /sbin – Stores executable files used by the administrator
C: /dev – Stores device drivers
D: /etc – Contains system configuration files

Practical Exercises:

1. Shell Script 1:

#!/bin/bash
option=4
while [ $option -ne 0 ]
do
  echo "MENU"
  echo "1) Display the contents of a file"
  echo "2) View files in a directory"
  echo "3) Show Time and Date"
  echo "4) Exit"
  read option
  case $option in
    1)
      clear
      echo "Please fill in the name of the file"
      read file
      if [ -e "$file" ]; then
        if [ ! -f "$file" ]; then
          echo "The parameter is not a file"
        else
          cat "$file"
        fi
      else
        echo "Error: File does not exist"
      fi
      ;;
    2)
      clear
      echo "Enter the directory you want to see"
      read directory
      if [ -d "$directory" ]; then
        if [ ! -d "$directory" ]; then
          echo "The parameter is not a directory"
        else
          ls -l "$directory"
        fi
      else
        echo "Error: Directory does not exist"
      fi
      ;;
    3)
      clear
      date
      ;;
    4)
      exit
      ;;
  esac
done

2. Shell Script 2:

#!/bin/bash
echo "Enter directory to check:"
read directory
if [ -d "$directory" ]; then
  cont=0
  for dir in $(ls "$directory"); do
    if [ -d "$directory/$dir" ]; then
      cont=$(expr $cont + 1)
    fi
  done
  echo "$directory contains $cont subdirectories"
else
  echo "$directory is not a directory"
fi

3. Shell Script 3:

#!/bin/bash
if [ $# -eq 1 ]; then
  cd "$1"
  for i in *; do
    if [ -d "$i" ]; then
      echo "$i is a directory"
    else
      cat *.* >> /home/directory/file.txt
    fi
  done
else
  echo "The program requires that you pass a directory as a parameter"
fi