[libvirt] [PATCH] maint: avoid spurious output if program not present
Eric Blake
eblake at redhat.com
Mon May 10 20:58:37 UTC 2010
On 05/10/2010 02:19 PM, Eric Blake wrote:
> Some shells warn about missing programs before redirection;
> the idiomatic way to silence them is to run the program check
> inside a subshell, with the redirections outside the subshell.
>
> +++ b/cfg.mk
> @@ -252,7 +252,7 @@ sc_prohibit_trailing_blank_lines:
> preprocessor_exempt = (remote_(driver|protocol)\.h)$$
> # Enforce recommended preprocessor indentation style.
> sc_preprocessor_indentation:
> - @if (cppi --version >/dev/null 2>&1); then \
> + @if (cppi --version) >/dev/null 2>&1; then \
Offlist, Jim reminded me that cfg.mk is only for developers with nice
environments, where we shouldn't need the subshell at all...
> $(VC_LIST_EXCEPT) | grep '\.[ch]$$' \
> | grep -vE '$(preprocessor_exempt)' | xargs cppi -a -c \
> || { echo '$(ME): incorrect preprocessor indentation' 1>&2; \
> diff --git a/src/Makefile.am b/src/Makefile.am
> index fe33cea..1542ab1 100644
> --- a/src/Makefile.am
> +++ b/src/Makefile.am
> @@ -169,7 +169,7 @@ EXTRA_DIST += remote/remote_protocol.x remote/rpcgen_fix.pl
> # * remove white space at end of buffer
> .PHONY: remote_protocol-structs
> remote_protocol-structs:
> - $(AM_V_GEN)if pdwtags --help > /dev/null 2>&1; then \
> + $(AM_V_GEN)if (pdwtags --help) > /dev/null 2>&1; then \
But here, not only is Solaris /bin/sh noisy (which we are starting to
care less about these days, because it is so crufty), but so is FreeBSD
8.0 /bin/sh, which is a lot newer. And since it appears as part of the
user's Makefile, rather than development-specific, it should be silent.
Given that analysis, Jim gave the off-list ACK.
So I've kept the second hunk as-is, modified the first to drop the
subshell altogether, and pushed.
--
Eric Blake eblake at redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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