For loop in Shell Scripting

For loop is used for looping a range of values, which can be any set of strings.

Syntax for loop

for variable in values

do

statements

done

During each pass through the loop, variable takes on the value of each successive variable in the values.

Example

#!/bin/sh for var in page linux dot com do echo $var done exit 0

We get the output:

page

linux

dot

com

How it works

Here a variable var is created and defines a different values in each loop. First time it assigns value page, for next loop next value linux is assigns for var and so on.

Using for loop for counting till 10 in different ways.

#!/bin/bash for a in 1 2 3 4 5 6 7 8 9 10 do echo -n "$a " done echo exit 0

#!/bin/bash for a in `seq 10` do echo -n "$a " done echo exit 0

#!/bin/bash for ((a=1; a <= 10 ; a++)) do echo -n "$a " done echo exit 0

Use double bracket after for in last example.

Use -n option after echo for display output in same line. Without  -n option each output will print on display in new line.