A concise tutorial on shell script for loop statements _linux Shell

Like other programming languages, the shell supports A for loop.

For loops The general format is:

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For variable name in list
Todo
Command1
Command2
...
CommandN
Done

When the value of the variable is in the list, the For loop executes all the commands at once, using the variable name to get the current value in the list. The command can be any valid shell command and statement. The in list can contain replacements, strings, and file names.

The in list is optional, and if it is not used, the For loop uses the positional parameters of the command line.

For example, sequentially prints a number in the current list:

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For loop in 1 2 3 4 5
Todo
echo "The value is: $loop"
Done

Output:
The value is:1
The value Is:2
The value Is:3
The value Is:4
The value Is:5

Characters in the sequential output string:

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For str in ' it ' a string '
Todo
Echo $str
Done

Output:
This is a string