[Haskell] ANNOUNCE: HsUnix 1.0.1 - Haskell for Unix Shell Scripting

Andrew Pimlott andrew at pimlott.net
Mon Feb 9 11:07:39 EST 2004

On Mon, Feb 09, 2004 at 12:49:28PM +0100, Tomasz Zielonka wrote:
> On Sun, Feb 08, 2004 at 09:36:16PM +0100, Volker Wysk wrote:
> > Error Handling
> >     Error handling is one thing which is done much more thoroughly in
> >     HsUnix than in shells. Failed programs won't be silently ignored.
> >     Dynamic exceptions are used for error handling. Non zero exit codes
> >     are thrown as exceptions.
> Most sh derivaties have -e set option, which causes the shell to (taken
> from FreeBSD sh man page):
>   -e errexit
>     Exit immediately if any untested command fails in non-interactive
>     mode.

It doesn't work.

    #!/bin/sh -e
    cat nosuchfile | echo hello

This script will exit with status 0 (success).  If you think about
how traditional unix shells are implemented, you will see that they
can't get this right.  (Which proves the non-existence of reliable
non-trivial shell scripts!)

I have my own half-finished shell-in-Haskell that handles this.  I
would be interested to know whether HsUnix does.


More information about the Haskell mailing list