Odd behavior of scripts in dos mode

Eric Blake eblake@redhat.com
Thu Apr 26 14:41:00 GMT 2012

On 04/26/2012 08:13 AM, Andrew DeFaria wrote:
> I remember that Cygwin used to not be able to run scripts that were
> converted or were in "DOS" mode - had trailing carriage returns in the
> file. It would fail because the #! line might have /bin/bash\r which was
> not a file (bash with a carriage return that is). But the behavior has
> changed. Now it seems to ignore the trailing carriage return and it
> execs bash itself. But it fails later on with other carriage returns.

If you want bash to ignore carriage returns, then ask it to do so:

> 4. This version of bash has a cygwin-specific set option, named "igncr",
> to force bash to ignore \r, independently of cygwin's mount style.  As
> of bash-3.2.3-5, it controls regular scripts, command substitution, and
> sourced files.  I hope to convince the upstream bash maintainer to
> accept this patch into a future bash release even on Linux, rather than
> keeping it a cygwin-specific patch, but only time will tell.  There are
> several ways to activate this option:
> 4a. For a single affected script, add this line just after the she-bang:
>  (set -o igncr) 2>/dev/null && set -o igncr; # comment is needed
> 4b. For a single script, invoke bash explicitly with the option, as in
> 'bash -o igncr ./myscript' rather than the simpler './myscript'.
> 4c. To affect all scripts, export the environment variable BASH_ENV,
> pointing to a file that sets the shell option as desired.  Bash will
> source this file on startup for every script.
> 4d. Added in the bash-3.2-2 release: export the environment variable
> SHELLOPTS with igncr included in it.  It is read-only from within bash,
> but you can set it before invoking bash; once in bash, it auto-tracks
> the current state of 'set -o igncr'.  If exported, then all bash child
> processes inherit the same option settings; with the exception added in
> 3.2.9-11 that certain interactive options are not inherited in
> non-interactive use.
> 4e. bash-4.1.9-1 dropped support for 'shopt -s igncr'; it did not make
> sense to support the option through both set and shopt, and SHELLOPTS
> proved to be more powerful.

Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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