90 Days of journey with trainwithshubham shell scripting command make us master in devops journey

Shell scripting is a powerful way to automate tasks on Unix-like operating systems such as Linux. Here are some common shell script commands:

Shebang: Indicates the interpreter to be used for executing the script.
```
  #!/bin/bash
```
Comments: Used for adding comments in the script for documentation.
```
  # This is a comment
```
Variables: Used to store data.
```
  variable_name="value"
```

Echo: Prints text or variables to the terminal.

  echo "Hello, world!"
  echo "The value of variable is: $variable_name"

Read: Reads input from the user.
```
  read -p "Enter your name: " name
```
If Statement: Conditional execution based on a condition.

COPY
```
  if [ condition ]; then
      # code block
  fi
```
For Loop: Executes a block of code a fixed number of times.

COPY

COPY
```
  for i in {1..2}; do
      # code block
  done
```
While Loop: Executes a block of code repeatedly as long as a condition is true.
```
  while [ condition ]; do
      # code block
  done
```

Functions: Blocks of reusable code.

   codemy_function() {
      # code block
  }

Command Substitution: Executes a command and stores the output in a variable.
```
result=$(command)
```

Conditional Execution: Execute commands based on the success or failure of previous commands.

command1 && command2   # command2 runs if command1 succeeds
command1 || command2   # command2 runs if command1 fails

File Operations:
- Create a file: touch filename
- Remove a file: rm filename
- Check if a file exists: if [ -f filename ]; then ...
- Check if a directory exists: if [ -d directoryname ]; then ...
Directory Navigation:
- Change directory: cd directoryname
- List files and directories: ls
- Make directory: mkdir directoryname
- Remove directory: rmdir directoryname
String Manipulation:
- Substring: Extracts a portion of a string.
```
    substring=${string:position:length}
```
- Concatenation: Combines two or more strings.
```
    concatenated="$string1$string2"
```
File Permissions:
- Change Permissions: chmod command.
```
    chmod permissions filename
```
- View Permissions: ls -l command.
Input/Output Redirection:
- Redirect Output: Sends the output of a command to a file.
```
    command > output_file
```
- Redirect Input: Provides input to a command from a file.
```
    command < input_file
```
Piping:
- Pipe (|): Sends the output of one command as input to another command.
```
    command1 | command2
```

Advanced Control Structures:

Case Statement: Executes different blocks of code based on matching patterns.

    case expression in
        pattern1)
            # code block
            ;;
        pattern2)
            # code block
            ;;
        *)
            # default code block
            ;;
    esac

Debugging:
- Print Debugging: Inserting echo statements for debugging purposes.
- Debugging Flags: Using set -x to enable debugging mode.
```
    #!/bin/bash
    set -x
    # script content
```

Functions:

Passing Arguments: Functions can accept arguments.

     codemy_function() {
        arg1=$1
        arg2=$2
        # code block
    }
    my_function value1 value2

Exit Codes:
- Exit Status: Every command returns an exit status.
- Checking Exit Codes: $? variable holds the exit status of the last command.
```
    command
    if [ $? -eq 0 ]; then
        echo "Command successful"
    else
        echo "Command failed"
    fi
```
Hshsh Operations:
- Usingexpr: expr command for basic arithmetic.
```
    sum=$(expr $num1 + $num2)
```

These command make you expert in Linux as well Devops journey