Top 10 Bash commands every new Bash developer should know

Here’s a list of the top 10 Bash commands every new Bash developer should know, drawn from elements of the provided script. These commands are foundational for scripting in Bash, providing a base for file manipulation, directory navigation, and executing commands:

1. echo - Used to display lines of text or variables. Frequently used for debugging scripts or showing instructions.

   echo "Usage: $0 <filename> <username> <hostname> <destination_directory>"
   

2. exit - Exits the current shell with a return code, useful for signaling success or failure of the script to the calling process.

   exit 1
   

3. if - Used for conditional branching in scripts, which lets you execute commands only if certain conditions are met.

   if [ ! -r $filename ]; then
       echo "Filename '$filename' does not exist"
       exit 1
   fi
   

4. [ ] - Test expression to evaluate conditions within if statements. It checks file attributes, string values, and performs arithmetic comparisons.

   [ $# -lt 4 ]
   

5. sftp - Secure File Transfer Protocol, a command used to securely transfer files over a network.

   sftp -q -b - $port_string $username@$hostname
   

6. cd - Changes the directory inside a script or a command line; it’s fundamental for navigation within the filesystem.

   cd $destination_directory
   

7. put - A command used within sftp sessions to upload files from local to remote systems.

   put $filename
   

8. bye - Exits an sftp session. It’s important to close sessions properly to free up resources.

   bye
   

9. -P (capital P in sftp) - Specifies the port number for connections, allowing the script to connect using non-default SSH ports.

   -P $port
   

10. -q (in sftp) - Stands for ‘quiet’; suppresses most of the command messages and progress meters, making output cleaner especially in automated scripts.

    sftp -q
    

These commands form the backbone of many scripting tasks in Bash and are critical for tasks such as automation, maintenance, and system administration.