Shell For Loops

For Loops

The while loop enables you to execute a set of commands repeatedly until some condition occurs. It is usually used when you need to manipulate the value of a variable repeatedly.

Syntax

for var in word1 word2 ... wordN
do
   Statement(s) to be executed for every word.
done

Example

#!/bin/sh

for var in 0 1 2 3 4 5 6 7 8 9
do
   echo $var
done

#!/bin/bash

for table in {2}
do
echo "table for 2: $table"
done

#!/bin/bash

for table in {2,3,4,5,6}
do
echo "table for 2: $table"
done

#!/bin/bash
for table in {2..20}
do
echo "table for 2: $table"
done

#!/bin/bash
for ((i=0; i<5; i++ ))
do
echo "the value is $i"
done

The list of values (Mon, Tue, Wed, Thu and Fri) are directly given after the keyword “in” in the bash for loop.

#!/bin/bash
i=1
for day in Mon Tue Wed Thu Fri
do
echo "Weekday $((i++)) : $day"
done

#!/bin/bash
i=1
for day
do
 echo "Weekday $((i++)) : $day"
done

$ ./forweek1.sh Mon Tue Wed Thu Fri