linux while bash code example
Example: shell script:while done
# The syntax is as follows:
while [ condition ]
do
command1
command2
command3
done
# command1 to command3 will be executed repeatedly till the 'condition'
# is true.
# The argument for a while loop can be any boolean expression.
# Infinite loop occurs when the conditional never evaluates to false.
# Here is the while loop for a one-liner syntax:
while [ condition ]; do commands; done
while control-command; do COMMANDS; done
# For example, the following while loop will print 'welcome x times' 5 times
# on the screen:
#!/bin/bash
x=1
while [ $x -le 5 ]
do
echo "Welcome $x times"
x=$(( $x + 1 ))
done
# as one-liner:
x=1; while [ $x -le 5 ]; do echo "Welcome $x times" $(( x++ )); done
# Here is a sample shell code to calculate factorial using while loop:
#!/bin/bash
counter=$1
factorial=1
while [ $counter -gt 0 ]
do
factorial=$(( $factorial * $counter ))
counter=$(( $counter - 1 ))
done
echo $factorial
# To run just type:
$ chmod +x script.sh
$ ./script.sh 5