expand:tldr:1b402

The command "expand -t=${1,4,6}" is used to expand tab characters to spaces.

Here is an explanation of each part of the command:

• "expand" is the command itself, which is used to expand tabs.
• "-t" is an option that specifies the tab stops.
• The "${1,4,6}" part is called brace expansion, which defines the tab stops to be used. In this case, it expands to three tab stops: 1, 4, and 6. This means that the first tab is expanded to 1 space, the second tab to 4 spaces, and the third tab to 6 spaces.

For example, if you have a file with the following content:

Hello    World

Running the command "expand -t=${1,4,6} file.txt" will replace the tabs in the file with spaces according to the tab stops defined. The resulting output could look like this:

Hello World

Here, the first tab is replaced with a single space, the second tab is replaced with four spaces, and the third tab is replaced with six spaces.