The for Command

Iterating through a series of commands is a common programming practice. Often, you need to repeat a set of commands until a specific condition has been met, such as processing all the files in a directory, all the users on a system, or all the lines in a text file.

The bash shell provides the for command to allow you to create a loop that iterates through a series of values. Each iteration performs a defined set of commands using one of the values in the series. Here's the basic format of the bash shell for command:

 for var in list
 do
    commands
 done

You supply the series of values used in the iterations in the list parameter. You can specify the values in the list in several ways.

In each iteration, the variable var contains the current value in the list. The first iteration uses the first item in the list, the second iteration the second item, and so on until all the items in the list have been used.

The commands entered between the do and done statements...