join:tldr:ca99f

The command "join ${file1} ${file2}" is used to combine the contents of two files based on a common field.

• ${file1} and ${file2} are placeholders for the actual filenames that need to be specified in the command.
• The command assumes that both files have the same format, and one or more fields in each file can be used to join them.

The "join" command identifies the commonly shared field in both files and merges them based on that field. It works as follows:

1. The command reads both files and sorts them based on the join field.
2. It compares the join field of each record in both files.
3. If the join field matches in both files, the command combines the matching records into a single line. It appends the fields from the second file to the first file.
4. The combined result is printed to the console or redirected to an output file, depending on how the command is used.

In summary, the "join" command is used to join two files by a common field, creating a new file that combines the content from both files.