simple while loop in bash

Question

I've started learning bash scripting. I wrote simple while loop, but it doesn't work. it's say that : command not found.does anybody knows why ? Here is my code:

let x=5; while [$x -lt 10];do echo "x is : $x";let x=$x+1; done

Answer 1

Add spaces.

while [ $x -lt 10 ];

For more information, please see this answer to How to use double or single bracket, parentheses, curly braces:

A single bracket ([) usually actually calls a program named [; man test or man [ for more info. Example:

$ VARIABLE=abcdef
$ if [ $VARIABLE == abcdef ] ; then echo yes ; else echo no ; fi
yes

Also, this is what info test has to say on the matter:

'test' has an alternate form that uses opening and closing square brackets instead a leading 'test'. For example, instead of 'test -d /', you can write '[ -d / ]'. The square brackets must be separate arguments; for example, '[-d /]' does not have the desired effect. Since 'test EXPR' and '[ EXPR ]' have the same meaning, only the former form is discussed below.

Therefore, the equivalent would look like:

let x=5; while test $x -lt 10;do echo "x is : $x";let x=$x+1; done