Shell Programming and Scripting

That is bash/ksh only, it is not POSIX compliant, which is why I suggested count=$((count+1))

---------- Post updated at 11:22 ---------- Previous update was at 11:20 ----------

let and ++ are ksh/bash only, not POSIX

Instead of ++ you can use a direct assignment in POSIX like this:

Code:

i=0
while [ $((i+=1)) -le 5 ]; do
  echo $i
done

@Scruti :

I have just tried the following look ... funny behaviour :

Code:

$ exec /usr/xpg4/bin/sh
$ let i++
/usr/xpg4/bin/sh: i++: bad number
$ let i+=1
/usr/xpg4/bin/sh: i+=1: bad number
$ i=0
$ let i++
/usr/xpg4/bin/sh: i++: more tokens expected
$ let i+=1
$ echo $i
1
$

... it just demonstrates what you said

Just a small correction: I believe POSIX suggests the following syntax:

Code:

count=$(($count+1))

Since /usr/xpg4/bin/sh on Solaris is actually an adapted Korn shell, it may well understand "let". It is however not part of POSIX.

OMG ... so on my machine, where should i go to find a POSIX shell ???
Lol

I haven't come across a situation where leaving out the $-sign did not work. Also, I found this:
Arithmetic Expansion

---------- Post updated at 12:03 ---------- Previous update was at 12:00 ----------

It is a POSIX compliant shell and so are ksh93 and bash. It is just that it may have some additional features that are not POSIX compliant.. If you want your code to work universally in all POSIX compliant shells you should avoid using those features.

Yeah i meant : on my machine, where should i go to find a pure POSIX shell (no additional feature) ...( that was to test the "let" behaviour)

But anyway, i think that ... unless we meet special case (with strong cross system compatibility constraints and requirements) , i prefer to take advantage of the new fonctionalities offered by ksh or bash even if not purely POSIX compliant.