The program takes input but show the following errors, how to resolve those errors ?

CodePudding user response：

[ is not mere syntax, it's a command, therefore it needs space to separate it from its arguments.

while [ $counter -le $number ]
# .....^....................^

Make sure you validate that number is actually only digits.

Some other comments:

• Use $(...) instead of `...` -- see https://github.com/koalaman/shellcheck/wiki/SC2006 for more details.
• bash can do arithmetic, you don't need to call out to expr. See Arithmetic Expansion and Shell Arithmetic in the manual. There is also an arithmetic conditional construct (analogous to the string-oriented [[...]] conditional construct) -- see Conditional Constructs and scroll down to ((...)) (there's no direct link).

CodePudding user response：

I think you need to add a space after [ and before ]:

#!/bin/bash

echo "Enter the number to find it's factorial"
read number
total=1
counter=1
while [ $counter -le $number ];
do
    total=` expr $counter \* $total`
    counter=` expr $counter   1`
done
echo $total

Working here on Ubuntu:

$ ./factorial.sh 
Enter the number to find it's factorial
5
120

CodePudding user response：

Actually, on line 7, you forgot the completing backtick.