# Cygwin bash **URL:** \ **Category:** Factual Questions\ **Created:** [February 25, 2003, 5:58pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439 "2003-02-25T17:58:58Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [February 25, 2003, 5:58pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439/1 "2003-02-25T17:58:58Z")
Is there any reason (other than I’m an idiot) that I can’t invoke built-in commands (e.g., typeset) from within a shell script? It’s a problem that I’ve never encountered before, running the same scripts under UWIN’s ksh, or, before that, on a real-deal Unix account (also ksh). I suspect it has something to do with my profile (which is whatever Cygwin’s default is – I just installed it), but can’t tell. Also, for arithmetic operations, the syntax shown in the O’Reilly book, _Learning the bash Shell_, doesn’t seem to work (e.g., **let x=1+3** or **$((1+3))**, and I have to go back to the old **expr** construct. Any ideas? Cygwin tells me it’s bash 2.05b, and it’s running on top of Windows 2000, even though I don’t think that matters. Thanks much. ---
**Author:** ![ChordedZither](https://avatars.discourse-cdn.com/v4/letter/c/e9c0ed/32.png) [@ChordedZither](https://boards.straightdope.com/u/ChordedZither)\ **Post date:** [February 25, 2003, 6:21pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439/2 "2003-02-25T18:21:10Z")
Shell scripts under Cygwin are usually running under **sh** (which is actually a renamed ash in CygWin) rather than under **bash**. The built-in commands for the two are quite different. If you really need your script to run with **bash** features, start your script with the line **#!/bin/bash** ---
**Author:** ![lothos2002](https://avatars.discourse-cdn.com/v4/letter/l/df788c/32.png) [@lothos2002](https://boards.straightdope.com/u/lothos2002)\ **Post date:** [February 25, 2003, 6:27pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439/3 "2003-02-25T18:27:33Z")
Is this that leetspeek the youngens talk about?:dubious: Speak English, man! Sorry, but it just looks weird when you have no clue what it is about. 😃 ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [February 25, 2003, 6:31pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439/4 "2003-02-25T18:31:31Z")
No. Leetspeek is more like: “j00 h4v3 b33n j4cI\<3d bY Gr4nD m4st3r 0r4ng3 j00ce!” “You have been hacked by Grand Master Orange Juice. Fnord.” ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [February 25, 2003, 6:33pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439/5 "2003-02-25T18:33:54Z")
Amend “j4cI\<3d” to h4cI\<3d for the english word hacked. ---
**Author:** ![UnwrittenNocturne](https://avatars.discourse-cdn.com/v4/letter/u/6de8d8/32.png) [@UnwrittenNocturne](https://boards.straightdope.com/u/UnwrittenNocturne)\ **Post date:** [February 25, 2003, 6:37pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439/6 "2003-02-25T18:37:54Z")
If cygwin is running **sh** then I cannot help, but what O’reilly says (given your example) about **bash** is right, leading me to agree with **Chorded Zither** (love that name) about you not being under **bash**. ---
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [February 25, 2003, 6:40pm UTC](https://boards.straightdope.com/t/cygwin-bash/157439/7 "2003-02-25T18:40:02Z")
**ChordedZither** : Just tried **#!/bin/bash** , and it seems to work. Thanks! It’s been a loooooong time since I’ve used the Bourne shell, and actually I’d really like to stick with ksh, but UWIN was serious misbehaving, so I’m giving Cygwin a try (rather than spending big bucks on MKS Toolkit). As it is, I’m finding out there are lots of differences between ksh and bash, too, but oh well.