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
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1 Answer
Add spaces.
while [ $x -lt 10 ];
For more information, please see this answer to How to use double or single bracket, parentheses, curly braces:
A single bracket (
[) usually actually calls a program named[;man testorman [for more info. Example:$ 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
1 Comment
Mark Reed
Exactly. The conditional
[...] is just a shell command, and like any other command, the command name ([) has to be separated from its arguments (-lt 10 ]) by space.