Linux Split, Rejoin, and Shell Scripting Basics

Introduction

As a programmer working with Linux, it's essential to know some of the basics of shell scripting, which are essential for automating tasks and configuring systems. In this tutorial, we will explore two essential Linux commands: split and rejoin. We will also briefly cover some of the basics of shell scripting.

The Split Command

The split command is used to split large files into smaller chunks. This command is useful when you need to transfer large files over the network or store large files on limited space. The syntax for the split command is as follows:

split [OPTION]... [INPUT [PREFIX]]

• [OPTION]: Options can be used to specify things like the size of the chunks, the naming convention for the output files, etc.
• [INPUT]: The name of the input file that you want to split.
• [PREFIX]: The prefix for the output files. By default, the output file names are aa, ab, ac, etc.

Here's an example:

split -b 100M my_large_file.tar.gz my_large_file_split_

This will split the file my_large_file.tar.gz into smaller 100MB chunks, and the output files will be named my_large_file_split_aa, my_large_file_split_ab, my_large_file_split_ac, etc.

The Rejoin Command

The rejoin command is used to join the chunks created by the split command back into a single file. The syntax for the rejoin command is as follows:

cat [FILE]...

• [FILE]: The files that you want to join together.

Here's an example:

cat my_large_file_split_?? > my_large_file.tar.gz

This will join all the files that start with my_large_file_split_ and end with two characters (the question marks) into the file my_large_file.tar.gz.

Shell Scripting Basics

In addition to split and rejoin, shell scripting is an essential skill for Linux programmers. Shell scripts are simply text files that contain commands that can be executed in a shell. Here are a few basics:

• Shebang: The shebang (#!) line is used to tell the shell which interpreter to use when running the script. For example, #!/bin/bash specifies that the script should be run using the Bash shell.
• Variables: Variables can be used to store values that can be used later in the script. For example, my_variable="hello" will assign the string "hello" to the variable my_variable.
• Command substitution: Command substitution allows you to use the output of a command as input to another command. For example, echo $(ls) will print a list of files in the current directory.
• Loops: Loops can be used to execute a command multiple times. For example:

for i in {1..5}; do
    echo "Hello, world!"
done

This will print "Hello, world!" five times.

Conclusion

In this tutorial, we covered the basics of the split and rejoin commands, as well as some of the basics of shell scripting. Hopefully, this will give you a good starting point for working with Linux as a programmer.